Monday, January 14, 2008
Pine Needle Scale
Homoptera: Diaspididae, Phenaeaspis pinifoliae
Scotch, mugho, Austrian Pine; also present but seldom damaging on Eastern White Pine, Norway Spruce, and some other conifers.
Description of Damage
Damage is not apparent until large populations have been present for more than 1 or 2 seasons. trees are stunted, grow slowly, have short needles and shoots. Occasionally the feeding of scales produces chlorotic, yellowish flecks no the needles, but normally this is not apparent. Heavily infested plants are seriously weakened and may be in a state of decline.
Scale covers are about 1/8" long, white, elongate, narrow in front and broad in back. Eggs under the scale covers are purplish in color. Crawlers and settled nymphs are reddish brown. Females are reddish in color beneath the white scale covers.
The hatching period is relatively short (7-10 days) in mid May and again in mid to late July. The first generation crawlers settle on old needles, since new growth is not fully developed until later. Second generation crawlers settle primarily on the current year's growth. Females produce 5-30 reddish purple eggs. Although the number of eggs laid is relatively small, two generations a year permits rapid buildup of infestations. In areas where infestations are large, lady beetle (especially the twice-stabbed lady beetle) is an effective predator.
Sprays are effective if applied after most eggs have hatched. Experience has shown that treatments for the summer generation may be more effective than the first. Control may be applied at either time.
Pine needle scale can be a serious pest of Christmas trees as well as ornamental trees and shrubs. Crawlers are blown by the wind and can be carried on birds.
Homoptera: Coccidae, Palvinaria innumerabilis
PLANTS ATTACKED: Maples and dogwood primarily, but also many woody ornamentals.
DESCRIPTION: Heavily infested plants will have large numbers of scales on the branches and twigs. Large numbers of feeding scales will reduce the amount of nutrients reaching the leaves and will cause them to turn yellow and fall prematurely. Scale insects feed on plant sap with their long thread-like mouthparts (stylets), which are six to eight times longer than the insect itself. Feeding by scales slowly reduces plant vigor. Heavily infested plants grow poorly and may suffer dieback of twigs and branches. Occasionally, an infested host will be so weakened that it will die.
IDENTIFICATION: During the winter the cottony maple scale is in the immature stage and is small, oval and flattened in shape, and pale green in color. During the warm temperatures of spring, the scale reaches maturity and, by late spring, the brown, elongate scale has a characteristic white, cottony egg mass attached to it.
LIFE HISTORY: Eggs are laid in April and June and hatching occurs throughout the early summer. Crawlers settle on leaves and stems. Male scales complete development by fall and mate with the immature females. Before the leaves drop from the trees, the female scales migrate to the stems and twigs to overwinter. In spring the female reaches maturity and lays a distinctive cottony egg mass. There is one generation per year.
CONTROL: Crawlers are usually out between June 5 and June 25 in Virginia. Treat June 10 and 20. Adult scales are protected from insecticides by waxy coverings. Control measures, therefore, must be aimed at unprotected immatures, called crawlers, which are only out for a short time. Dormant oil can be applied to the overwintering stages in late spring before new growth starts. During the growing season, when dormant oil cannot be used, insecticide treatments must be timed correctly to eliminate the crawler stage. See the Virginia Pest Management Guides for specific insecticides for control. Care should be taken when applying insecticides, because they may deplete the number of natural enemies that normally control the pest insects.
REMARKS: Cotton maple scales are heavily fed upon by natural enemies and, in some cases, chemical controls are not needed. English Sparrows, feeding on the scales are thought to be important in reducing populations. This scale is sometimes confused with Maple Leaf Scale, which produces its egg mass on the leaves. The Cottony Maple Scale produces its egg mass primarily on the branches and stems.
Empoasca fabae (Harris), Cicadellidae, HEMIPTERA)
Adult - Because many species of leafhoppers look alike, entomologists studying these insects must rely heavily on examination of internal genitalia structures, as well as external morphological characters, to distinguish the various species. The mature potato leafhopper is about 3 mm long, wedge-shaped, and winged. Generally greenish, it has very small, yellowish, pale, or dark green spots, and readily jumps when disturbed.
Egg - About 1 mm long, the egg is elongate and whitish.
Nymph - Several nymphal stages exist, all of which are wingless and smaller than the adult. Though paler, the nymph is colored similarly to the adult.
Distribution - During the summer, potato leafhoppers are found from the Atlantic coast to the Rocky Mountains. They are absent throughout most of the winter which they spend in the Gulf States. Northeastern and midwestern states suffer the greatest forage loss from this pest due to the concentration of alfalfa and clover in these areas. In North Carolina, these leafhoppers are widely distributed during the growing season on peanuts, hay and pasture crops.
Host Plants - This leafhopper feeds on more than 100 cultivated and wild plants, including bean, potato, alfalfa, soybean, and peanut. In North Carolina, peanuts are more seriously affected by this pest than are forage and pasture crops.
Damage - Nationwide, the potato leafhopper is a very injurious pest of forages, particularly alfalfa and clover. Both nymphs and adults feed on the undersides of the leaves. By extracting the sap, they cause stunting and leaf curl, as well as the condition called "hopperburn." This disease is caused by the injection of a toxic substance. It is characterized by a yellowing of the tissue at the tip and around the leaf margin which increases until the leaf dies. Symptoms are sometimes confused with drought stress.
Life History - Potato leafhoppers winter in the Gulf States and migrate northward in spring. They arrive in North Carolina in early summer. After mating, eggs are laid inside the veins on the underside of leaves. A female leafhopper lives about a month, producing one to six eggs daily. Eggs hatch in about 10 days, and the nymphs mature in about 2 weeks. Mating occurs approximately 48 hours after maturation. Three or four generations are produced each year in North Carolina.
When populations become severe, insecticides are the only practical method of leafhopper control.
Aphids, or plant lice, are small, soft-bodied insects which are common pests of nearly all indoor and outdoor ornamental plants, as well as vegetables, field crops, and fruit trees. There are hundreds of different species of aphids, some of which attack only one host plant, while others attack numerous hosts. Most aphids are about 1/10 inch long, and though commonly green and black, they may be gray, brown, pink, red, yellow, or lavender. A characteristic common to all species is the presence of two tubes, called cornicles, on the back ends of their bodies. The cornicles secrete defensive substances. In some species they are quite long, while in others they are very short and difficult to see.
Aphids feed in clusters and generally prefer new, succulent shoots or young leaves. Some species, known as woolly aphids, are covered with white, waxy filaments which they produce from special glands.
Life History: Aphids have unusual and complex life cycles which allow them to build up tremendous populations in relatively short periods of time. Most species overwinter as fertilized eggs glued to stems or other parts of plants. Nymphs which hatch from these eggs become wingless females known as stem mothers. There are no males present at this time. Stem mothers reproduce parthenogenetically (without mating), and their eggs are held within their bodies until they hatch so that young are born alive. All offspring are females which soon mature and begin to reproduce in the same manner. This pattern continues for as long as conditions are favorable. A dozen or more generations are typical in Virginia. Periodically, some or all of the young develop wings and migrate to other plants. Some species always settle on the same type of plant; others have one or more alternate hosts. With the return of autumn's shorter days and cooler temperatures, a generation appears which includes both males and females. After matting, these females lay the fertilized eggs which overwinter and eventually hatch into stem mothers the following spring. Aphids are in the order Homoptera, Family Aphididae.
Damage: Aphids feed by sucking up plant juices through a food channel in their beaks. At the same time, they inject saliva into the host.
Light infestations are usually not harmful to plants, but higher aphid populations cause leaf curl, wilting, stunting of shoot growth, and delay in production of flowers and fruit, as well as a general decline in plant vigor. Some aphids are also important vectors of plant diseases, transmitting pathogens, particularly viruses, in the feeding process.
A distinctive feature of aphids, as well as some scales and other bugs, is the production of honeydew. Honeydew is the clear, sticky dropping that lands on the leaves or anything below the plant or tree that aphids are feeding upon. A sticky glaze of honeydew may collect on lower leaves, outdoor furniture, cars, and other objects below aphid feeding sites. Honey dew coated objects soon become covered by one or more black or brown fungi known as sooty molds. Crusts of sooty mold are unsightly on man-made objects, and they interfere with photosynthesis in leaves.
Colonies of aphids are sometimes protected by certain ants. In return for this protection the ants are allowed to collect the sweet honeydew. In most cases, the ants protect aphids that have already established themselves on the plant and these aphids or their eggs and keep them through the winter in their nests. In spring, the ants transport these aphids to food plants where they protect them from enemies and at intervals transfer them to new feeding sites.
Recognition: Unthrifty or stunted plants and plants with curled or deformed leaves are likely to have aphid infestations. Feeding aphids usually occur in clusters on succulent shoots, under leaves, or in other suitable feeding sites. The presence of honeydew or sooty mold is often an excellent clue that aphids are present. Plants should be examined closely on a regular basis to detect aphids before damage is evident.
Some Common Aphids in Virginia:
White Pine Aphid. Black or gray with long legs. This is a common pest of eastern white pine. Severe infestations reduce the growth and may even kill small trees. Colonies occur most commonly on twigs and stems where the bark may be killed in patches. Needles and twigs are sometimes completely covered with sooty mold. Eggs, which are laid in lines on the needles, may hatch when infested white pines are brought indoors for use as Christmas trees.
Rose Aphid. Green or pink with black legs. A widespread and common pest of all cultivated roses, this species may also damage pyracantha. Stems, buds, and young, tender leaves are injured.
Giant Bark Aphid. Ash gray with black spots. Nearly ½ inch long including the legs, this is our largest aphid species. It attacks willow, maple, elm, birch, and several other common shade trees. It feeds on the bark of twigs and small branches. Bees, wasps, and flies are attracted to the honey-dew it excretes.
Green Peach Aphid. Pale yellow-green. This species attacks dozens of different hosts including aster, catalpa, crocus, chrysanthemum, dahlia, English ivy, iris, lily, nasturtium, pansy, rose, snapdragon, tulip,and violet, as well as many garden vegetables and some fruit trees. It is capable of transmitting over 100 different plant viruses.
Chrysanthemum Aphid. Shiny dark brown with short cornicles. Common and widespread on chrysanthemum where they cause stunted growth and slightly curled leaves.
Woolly Alder Aphid. Plump and blue-black, but completely covered with white waxy filaments. Silver maple is the primary host, but they migrate to alder in mid-summer, then return to silver maple in late fall. This aphid is not particularly injurious to either host, but it becomes a nuisance when waxy filaments accumulate under heavily infested trees.
Also, Woolly Apple Aphid, Rosy Apple Aphid, Pea Aphid, Cabbage Aphid, Bean Aphid, Mellon Aphid, Snowball Aphid, and many, many others. Some aphids cause galls. Included in this group are:
Witchhazel Cone Gall Aphid, Spiny Witchhazel Gall Aphid, and the Elm Cockscomb Gall Aphid.
Control: Natural enemies play a very important part in controlling aphid populations. Lady beetles, lacewings, damsel bugs, flower fly maggots, certain parasitic wasps, birds, and fungal diseases all attack aphids. Without them, these pests would be much more destructive. Gardeners should avoid unnecessary use of insecticides which are harmful to beneficial organisms.
Gardeners should also strive to keep their plants healthy and growing vigorously. Migrating aphids are attracted to the yellow-green color of unthrifty plants. If an infestation does develop, there are several insecticides registered for aphid control. Check the Virginia Pest Management Guides for current pest control recommendations. These guides are available through your local Extension agent. Always read the label before applying any pesticide.
This Law states That The Following Plants Cannot Be Planted, Bought or Sold In Illinois Without A Permit.
Natural Resources. Such permits shall be issued only for experiments in controlling and eradicating exotic weeds or for research to demonstrate that a variety of a species listed in this act is not an exotic weed." The act defines exotic weeds as "plants not native to North America, which when planted either spread vegetatively or naturalize and degrade natural communities, reduce the value of fish and wildlife habitat, or threaten an Illinois endangered or threatened species....Violators of this act shall be guilty of a class B misdemeanor. When the violation is a continuing offense, each day shall be considered a seperate violation. "Furtermore. "exotic weeds offered for sale in Illinois....(to Illinois residents) are subject to confiscation and destruction by agents of the Department of Natural Resources." However commercially propagated exotic weeds for sale outside Illinois are permissible. Weeds that are exotic in Illinois are noted in table 4.2
Table 4.2 Exotic weeds of Illinois
Japanese Honeysuckle (Lonicera japonica)
Multiflora rose (Rosa Multiflora)
Purple Loosestrife (lythrum salicaria)
Certain weeds have been legally declared Noxious by the Illinois legislature. There control is required by law. The Illinois Noxious Weed states that "every person shall control the spread of" and "eradicate all noxious weeds on lands owned or controlled by him in the state of Illinois." "Whenever the owner or person in control of the land on which noxious weeds are present has neglected or failed to control them, the control authority having jurisdiction shall have proper control and eradication methods used on such land, and shall advise the owner,person in control, and record holder of any encumbrance of the cost incurred in connection with such operation. The cost of any such control or eradication shall be the expense of the owner. In addition the person shall be subject to a fine of not more than 100 dollars for the first offense and not more than 200 dollars for each subsequent offence. The weeds that are noxious in Illinois are noted in Table 4.1. The local county weed commissioner can also declare certain weeds as noxious in the county under his or her jurisdiction.
Common ragweed (ambrosia artemisiifolia)*
Giant ragweed (Ambrosia trifida)*
Marijuana (Canbnabis sativa)
Musk Thistle (Cirsium arvense)
Johnson Grass (Sorghum halepense)
Perennial sowthistle (Sonchus arvensis)
Sorghum - Almum (Sorghum almum (Sorghum almum)
*Noxious only within the corporate limits of the cities, villages, and incorporate towns.
Wednesday, January 9, 2008
Sunny Knock Out® PPAF
Introducer: The Conard-Pyle Co.
Breeder William Radler
Type Landscape Shrub Rose
Color: Bright Yellow
Size: Medium (2 inches)
Color: Bright yellow at opening, turning
cream white when fully open
Number of Petals: mostly 5, sometimes 6
Diameter: 3 inches
Fragrance: no flower fragrance, but the petioles release a strong sweetbriar fragrance similar to Rainbow Knock Out®
Vegetation: Very vigorous
Inflorescence: 1 to 5 flowers per stem
Foliage: dark green, semi glossy
Disease Tolerance: Very good
Flowering: very abundant and continuous, will bloom year round in mild climates
Height: 4 - 4 1/2 feet
This new release from Bill Radler has the disease resistance of the original Knock Out®, with a similarly dark, attractive foliage, and a slightly more upright habit. A new color in the most popular shrub rose family in North America, Sunny Knock Out® will shine in any garden from Canada to the Gulf. Winter hardy to zone 4. The yellow color will stay stronger during the cooler times of the year.
Tuesday, December 18, 2007
Candelabra Plant, Elkhorn
Euphorbia lactea is a cactus-like plant with 3 or 4 angled branches that are deeply scalloped with black spines. It is used medicinally in India as a hot jam to treat rheumatism. All plant parts are considered poisonous, especially the white, milky sap. It is irritating to the skin, eyes and mouth. Euphorbia lactea need full sun to partial shade with warm temperatures. We use a soil mix consisting of equal part of loam and sand. The plant should be allowed to dry thoroughly between waterings. In the winter months, water should be restricted to once over the winter. The most common failure in growing this plant is over-watering, especially during the winter months. Euphorbia lactea "Cristata" is an intricately monstrous form with fan-shaped crested branches forming a snaky ridge or crowded cluster. Crest form often needs in grafting.
Monday, December 17, 2007
Organic Greenroof Architecture: Sustainable Design for the
Making the most of your building's "fifth façade"
© Wiley Periodicals, Inc.
Environmental Quality Management/Summer 2005
By Linda S. Velazquez
High-performance buildings, green design practices, and sustainable
technologies are becoming increasingly important influences on architectural
practices around the world. They are even beginning to influence standards
within the construction industry.
Encouraged by growing interest and demand on the part of both the public
and private sectors, multidisciplinary professionals -- from architects to
environmental managers, from engineers to landscape architects and beyond --
are redefining the way we look at design and examining our environmental
impacts on the Earth with an integrated, holistic approach.
Green Building. Green Architecture. Green Roofs.
“Green” anything nowadays is a hot topic and a buzzword -- sometimes
wholeheartedly embraced, other times politically charged, sometimes even
scoffed at. But perhaps this design adjective should be accepted simply as a
common-sense approach and an indication of respect for both our natural and
But what constitutes "building green," and what does sustainability mean
in the context of building design? In the United States, the Office of the Federal
Environmental Executive defines green building as "the practice of (1) increasing
the efficiency with which buildings and their sites use energy, water, and
materials, and (2) reducing building impacts on human health and the
environment, through better siting, design, construction, operation, maintenance,
and removal -- the complete building life cycle.”1
The simplest definition of sustainability is design that meets the needs of
the present generation without compromising the ability of future generations to
meet their needs.
Noted green architect William McDonough asks us to imagine building
structures that not only do not hurt the environment, but that contribute positively
to ecosystems, and possibly even help heal disturbed landscapes.
The use of greenroofs on commercial buildings can help further the goal of
maximizing the eco-friendliness of the built environment.
About this Article
This article presents an overview of the greenroof concept. Included is
discussion of the history of greenroofs -- which, though relatively modern in their
present form, are rooted in ancient vernacular architecture and in the innate
human desire to connect the built environment with nature.
I discuss basic greenroof technologies, and explain some of the key
ecological, economic, aesthetic, and psychological advantages that greenroofs
offer to both users and owners.2
Global Concerns Drive the Search for Green Solutions
Several issues of global environmental concern have been driving a new
"greater green." Factors such as global warming, air and water pollution,
population growth, and loss of habitat and biodiversity have contributed to the
call for improved environmental design.
In a 2001 "Special Report on Global Warming," Time magazine noted that
the global mean temperature is expected to rise between 2.5ºF and 10.4ºF over
the next 100 years. The United Nations weather agency recently stated that
Earth's average temperature in 2001 was the second highest recorded since
global records began 140 years ago.
The Kyoto Protocol, which is aimed at slowing global warming by reducing
human impacts, went into effect in February 2005. The Protocol commits 35
industrialized countries -- the U.S. not among them -- to reducing their emissions
of six greenhouse gases (principally carbon dioxide) to five percent below 1990
levels by 2012.
Some other indicators of environmental stress include the following:
• The U.S. Census Bureau reports that at midyear 2002, the global
population reached 6.2 billion. The United States alone will be home to
420 million people by 2050, or 140 million more than in 2000.3
• Humans now consume natural resources 20 percent faster than nature
can renew them.
• Use of fossil fuels increased by almost 700 percent between 1961 and
• Populations of land, freshwater, and marine species fell on average by 40
percent between 1970 and 2000.4
• Impervious cover has become a signature effect of contemporary land use.
Our paving of open land and speculative development patterns resemble
an urban equivalent of the “slash and burn” clear-cutting techniques that
are still so prevalent in forestry and agriculture.
• As a result of our land use practices, we have developed over-stressed
sewer systems and urgent stormwater management problems.
In an era when developing clean and renewable energy strategies and
addressing ever-increasing energy consumption rates are so crucial to our
economic and ecological future, it is clear that we need to fully examine eco-
friendly alternatives that also make economic sense in order to truly create a
Global Answers Include Sustainable Greenroof Architecture
Greenroofs are not a panacea for our environmental construction ills. Nor
should any one single design component carry that burden. The beauty and
promise of sustainable architecture and design lie in the integration of roof,
building skin, interior, site location, and overall building design.
But viewed as one layer of a green building strategy, greenroofs can play
an important role. They can:
• reduce ambient air temperature, energy use, and utility costs;
• help cleanse the air and water;
• utilize local and recycled materials;
• extend the life of the roof;
• improve aesthetics; and
• create greenspace for humans and wildlife while providing a psychological
and physical respite from urban surroundings.
What Is a Greenroof?
What exactly constitutes a greenroof? Greenroofs are simply vegetated
roof covers constructed atop and across a roof deck. They sometimes are called
ecoroofs, sky gardens, even skyrise gardens. As living roofs, they contrast
starkly with the average inert, hot, barren roof.
The greatest potential of greenroofs lies in their capacity to cover
impervious roof surfaces with living, breathing, permeable plant material.
Greenroofs are healthy, sustainable, and regenerative roof landscapes that can
help protect our environment by diminishing developmental impacts on our
communities. They are one sustainable design element in the palette of today’s
Integrated Living Roofs
Integrated design is essential for delivering a cost-effective green building.
Successful practitioners have come up with ways to get the whole team
collaborating effectively and thinking outside the box. Not only are they
delivering green projects within conventional building budgets, but many are
doing it for a conventional fee.
As designers and community and business leaders, we can choose to
mitigate the many negative effects of a building’s footprint by incorporating
various green design principles. As an alternative to imposing our built structures
onto the land without considering the function of under-used roof surfaces
(beyond waterproofing), we can incorporate organic greenroof architecture as a
way of designing with nature to evoke displaced landscapes and restore a
measure of greenspace.
Imagine looking down from an airplane with a bird’s eye perspective.
Instead of seeing huge expanses of concrete or black tar roofs imposing
themselves on the natural environment, you see moving stands of flowering,
The roof now blends into the landscape as a naturalistic meadow scene.
Or designed gardens and parks create a new “fifth” façade for human recreation
with flowering shrubs, trees, and vegetated spaces.
These scenarios are technologically possible, and greenroofs do not
require particularly high-tech design. It is important to understand, however, that
these are engineered systems consisting of various material layers which must
work in tandem to perform correctly.
A Quick History of Greenroofs: From Ancient Mesopotamia to the 21st
Combining plants with architecture is not a new idea, and neither are
greenroofs. Since early recorded times, natural and created landscapes have
been integrated into the urban fabric.
Designed elevated greenspaces have existed as long as humanity has
been concerned with architecture. Manipulating our living spaces logically also
includes using natural areas and garden designs as artistic expressions and a
way to connect back to nature.
The sloping walls of the Ziggurat of Nanna, built around 2100 B.C., were
covered with trees and shrubs. The fabled Hanging Gardens of Babylon, which
included lush roof gardens and terrace greening, represent the earliest known
interpretations of roof greening, built between the 8th and 10th centuries B.C.
Earth-sheltered huts dating from the Viking era have been found in Ireland
and Scotland. In addition, around 1000 A.D., sod-covered roofs were used in
Iceland and Scandinavia. Later on, early 19th century settlers in Canada and the
northern United States introduced grass roofs.
"Garden cities" have been developed from Persia to Renaissance-era
Paris, and later from Russia to Berlin, London, and New York. Modernist
architects such as Le Corbusier, Frank Lloyd Wright, and Roberto Burle Max
promoted the benefits of roof gardens, and incorporated them into the fabric of
their designs. Still-successful modern greenroofs from the 1930s include the five
famous Rockefeller Roof Gardens in New York, and the Derry and Tom's Garden
in London (the modern Kensington Roof Gardens).5
Greenroofs today can be found throughout Europe and around the world.
But the development of greenroofs from an expression of vernacular architecture
to a viable sustainable construction roofing alternative took place in modern
Germany. There, greenroofs have evolved through trial and error, the repeated
testing of materials, and ultimately the development of industry standards and
codes. It is estimated that Germany now has over 800 greenroof projects.6
Modern Greenroof Pioneers in Germany and North America
True modern greenroofs were introduced in Germany in the early 1970s
by manufacturers, landscape architects, and university researchers. In 1971
Gerda Gollwitzer and Werner Wirsing outlined the principles of modern
greenroofs in their book entitled Roof Areas Inhabited, Viable, and Covered by
Vegetation. Hans-Joachim Liesecke outlined the basis for intensive greenroofs
in his 1972 report entitled Dach und Terrassengärten [Roof and Terrace
Gardens]. Others followed, notably Kolb, Hans Luz, Hans Kienle, and Bernd
Acceptance of greenroofs in the European marketplace came in the 1980s,
when systems were enhanced through use of reliable root barriers and
sophisticated forms of buildup that guaranteed safety and a long lifespan. Credit
for many of these developments goes to the German greenroof companies ZinCo,
optima (now split into two companies, optima and Optigrün), and Bauder. They
were the pioneers of modern greenroof technology, especially with regard to root
resistant bituminous waterproofing.
Pioneers and proponents of greenroofs in North America from the early
1990s include Tom Liptan, ASLA, of the City of Portland, Oregon; Charlie Miller,
P.E., of Roofscapes, Inc.; Katrin Scholz-Barth, a civil and environmental engineer;
and especially two prominent veteran landscape architects from the sphere of
traditional roof garden design -- Cornelia Hahn Oberlander, FCSLA, FASLA, in
Canada, and Theodore Osmundson, FASLA, in the United States.
Two Greenroof Types: Extensive and Intensive
Greenroofs are vegetated roofs with engineered soil (also known as the
substrate or growth media) and plants layered above a concrete, wood, or metal
roof deck. They can substitute for gravel, shingle or tiles. Imagine a roof
lasagna-like assembly with a meadow on top.
The bottom line is that the plants are planted directly onto the roof, not just
in containers. The layers vary from system to system, and certain elements vary
in their placement above the roof deck. At the very least, however, all greenroofs
include waterproofing (single or multi-ply), drainage, soil, and plants.
Over the past 35 years, sound German engineering, technology
developments, and testing standards have led to greenroof systems that range
from virtually maintenance free to quite elaborate.
There are two main types of greenroofs -- extensive and intensive (also
referred to as low-profile and high-profile); the names indicate maintenance
requirements. The two designs can also be combined.
The type of greenroof that is appropriate for a given application must be
determined by the site owner and designer, with a view to how the roof is to
function. Greenroofs can be used successfully in both new and retrofit
construction. They are limited only by the slope or pitch of the roof, existing load
requirements, and budget factors.
See Exhibit 1 on the following page for a chart describing the differences
between extensive and intensive greenroofs.
Extensive vs. Intensive Greenroofs
Low-Profile/ Ecoroofs High-Profile/ Roof Gardens
• Low growth media: 1”–6”
• Lightweight: 12 –50 lbs/sf
• Low growing plants: 1”–24”H
• Less variety of plants: Alpine
types, succulents, herbs, some
grasses and mosses
• Usually non-accessible
• Slopes up to 30°& higher
• Less expensive: $12-$25/sf
• Low water requirements
• Low maintenance
• > 6”-15’ and deeper
• Heavier weights: 50 lbs/sf +
• Trees, shrubs and more
• Huge variety of plant selection,
depending on loads, design &
• Designed for human recreation
• Relatively flat
• More expensive: $25-$40/sf +
• Irrigation usually necessary
• Higher maintenance
Extensive greenroofs employ fewer and thinner build-up layers, and thus
are lighter and less expensive systems. They are used when the owner primarily
desires an ecological roof cover with limited or no access for recreation. Less
growth media is used, and the appropriate plants are low-growing, hardy Alpine
Plants for extensive greenroofs must be tolerant of high heat, drought,
wind, and frost. They must also be self-regenerative in nature, and have low
maintenance requirements overall.
Media depths range from one inch up to about six inches. A popular
misconception is that a flat roof is ideal, but in fact flat roofs present drainage
issues. Ideally the roof should have a gentle slope of at least 1.5 - 2% to allow
for natural drainage properties. Generally, extensive greenroofs can be installed
on slopes of up to 30°, although there are greenroofs with 40° slopes.
Reinforcement will be necessary at steeper pitches using cross battens or
underlying grid structures to hold the plants and engineered soil in place, as well
as to deal with wind shear.
Roofs with strong wind uplift or with slopes 15° and higher should be
protected during establishment with an erosion control net in the form of jute or
other natural biodegradable fiber.
Intensive greenroofs look more like a traditional roof garden. They can
incorporate a much wider variety of plants (such as flowering shrubs, vegetables,
and even trees) because the substrate depths can be designed to be as deep as
the designed roof load will support. Depths start at about six inches up to 15 feet.
The main difference between a roof garden and an intensive greenroof is
that a greenroofing system is applied on top of the entire roof deck surface,
allowing unimpeded drainage and a more even weight distribution over the whole
Architectural accents -- such as waterfalls, ponds, seating areas, and the
like -- can be part of an intensive greenroof system. Such roofs can provide
recreation areas where people can interact with nature and with one another.
These systems can take advantage of otherwise forgotten (and usually ugly)
rooftop space by creating active areas for contemplation and play.
The Advantages of Greenroofs
Loss of greenspace and its inherent natural processes are by-products of
our modern "asphalt jungle." Plants and engineered soil atop a greenroof
enhance the environment through the natural processes of evapotranspiration
and photosynthesis, thereby ameliorating the surrounding ecosystem.
The specific benefits of (and market drivers for) greenroofs run the gamut
from easing environmental stress to creating an eco-friendly corporate image to
reestablishing endangered bird species. The following sections discuss the
advantages of greenroofs in more detail.
Greenroofs reduce stormwater volume and slow down water flow, thus
helping to alleviate the pressure on stormwater infrastructure systems.
Many large, older U.S. cities (such as New York, Philadelphia, and San
Francisco) have combined sewer systems where wastewater from storm drains
and sewage pipes is intermingled. During heavy rains, runoff from impervious
surfaces such as rooftops and pavements can cause overflow in already over-
burdened systems, resulting in contamination of lakes, rivers, and other
freshwater sources. Exhibit 2 shows the percentage of impervious cover that is
typical of various contemporary land use types.
Greenroofs capture and retain huge amounts of water that otherwise
would go down the storm drains, absorbing anywhere between 50 to 95 percent
of the rain that falls on site. Factors affecting retention rates include the intensity
of the storm, depth of media, and plant mass.
The intelligent use of best management practices (BMPs) includes
greenroofs that intercept and delay rainfall runoff and reduce the peak flow rate.
These practices can result in significant environmental improvements, as well as
long-term savings to building owners and municipalities.
Redrawn from Bruce Ferguson's "Introduction to Stormwater: Concept, Purpose, Design," 1998.
Water Quality Improvement
Greenroofs also filter and cool water runoff. They can help prevent
nitrogen, phosphorus, and toxins from entering streams and waterways. Heavy
metals and nutrients found in stormwater are bound in the engineered soil of the
greenroof instead of being discharged into groundwater or streams and rivers.
Greenroofs can remove over 95 percent of the cadmium, copper, and lead, and
16 percent of the zinc, from rainwater. They can also substantially reduce
Coastal cities such as Seattle and Portland, Oregon, have experienced
warming of the water in their rivers and bays resulting from discharge of heated
stormwater. This temperature change can greatly affect the health of cold water
fish populations, such as salmon.
Greenroofs can help counteract this effect. They act as a sponge,
absorbing the majority of rain that falls on site. The remaining water that does
eventually run off is filtered and cooled through evapotranspiration made possible
by the plants and engineered soil medium.
In natural landscapes, vegetative canopy biomass greatly lowers air
temperatures. By contrast, the artificial and altered surfaces common in urban
land- and roofscapes greatly raises them. Average city rooftops can easily reach
150 to 175°F in the summer.
In urban areas, tightly sealed surfaces -- such as asphalt and concrete in
parking lots and on rooftops -- soak up heat during the day and then reradiate it
back into the Earth’s atmosphere after sunset as thermal infrared radiation.
This creates an urban "heat island" effect, with the heat that is released at
night forming a dome of higher temperatures over the city. The temperature in
downtown Atlanta, Georgia, for example, often is 10°F warmer than that of the
surrounding outlying areas. Urban heat islands contribute to our growing global
warming problem, and can also affect the local weather by creating unproductive
Used on a large scale, greenroof infrastructure could help reduce the
urban heat island effect by lowering ambient air temperatures. A 2002 study in
Toronto by Environment Canada estimated that urban temperatures could dip by
1 to 2°C if just six percent of the city’s roof tops were green.8
Chicago has adopted an energy conservation ordinance that includes an
urban heat island reduction provision. The ordinance, which became effective in
June 2002, includes minimum standards for solar reflectance and emissivity as
set by the International ASTM (formerly known as The American Society for
Testing and Materials). The ordinance requires all new and refurbished roofs to
install greenroofs or reflective roofing.
Air Quality Improvement
In urban downtown areas, ventilation is sometimes inhibited by tall
buildings, which reduce wind speed and trap heat in air pockets. Pollutants can
remain suspended for days.
Greenroofs can filter and bind dust particles, and naturally filter airborne
toxins. Smog, sulphur dioxide, carbon dioxide, and other pollutants are absorbed
and filtered through the foliage, naturally cleansing the air. Atmospheric dust is
held until rain washes it off into the greenroof soil substrate.
Greenroofs can also help mitigate the ozone problem in urban areas by
reducing the heat island effect, which contributes to ozone creation. In Atlanta,
the heat island effect doubles the amount of ozone that is produced.
Studies have shown that an increase in ozone levels adversely affects
sufferers of asthma and other breathing conditions. Increasing vegetated areas,
including greenroofs, can greatly improve air quality.9
Erosion and Sedimentation Control
Greenroofs can help protect watersheds and sewer systems. They act as
erosion barriers by reducing stormwater volumes, and assist in the control of
sediment transport and soil erosion. Plants and media properties (friction, root
absorption, and substrate matter) can prevent substances from entering a stream
corridor or other body of water.
Wildlife Habitat Conservation, Creation, and Restoration
Although greenroofs are not intended to be replacements for natural areas
located at ground level, they nevertheless can provide some habitat for wildlife.
In a landscape ecological context, greenroofs create an artificial or man-made
edge, while also serving as a vegetative habitat patch.
These greenroof patches, set within the matrix of a city, can accomplish
several ecological functions. If multiple greenroofs were grouped and designed
as vegetated corridors, some semblance of landscape connectivity could be
Such corridors could offer respite for migrating birds and butterflies.
Studies show that birds will travel up to 19 stories, and butterflies up to 20 stories,
above ground in search of food and cover.
Even in densely populated areas, greenroofs can attract beneficial insects,
birds, bees, and butterflies. Such greenspace also can introduce or increase
biodiversity into a highly urbanized setting. In the UK and Switzerland, for
example, researchers are monitoring the levels of endangered bird, spider, and
other invertebrate species which were found to have come back to the city after
construction of greenroofs on previously disturbed sites.
Establishment of a thriving greenroof industry could have innumerable
effects on the economy, including the creation of many new jobs in
manufacturing, construction, and design, as well as in installation and other
Greenroof construction usually entails higher initial costs, but life cycle
analysis reveals that these costs can be offset through extension of the life of the
roof, avoided maintenance and replacement costs, reduction in cooling and
heating costs, increased developable space, reductions in local impact fees, and
the opportunity to take advantage of the amenity of greenspace at roof level.
Other economic benefits may be harder to quantify, but include acoustical
insulation (resulting in noise suppression effects ranging from 8 dB up to 50 dB),
glare reduction, decreased charges for stormwater infrastructure rehabilitation,
and the goodwill and publicity generated from having a high-profile greenroof
Some of the key economic benefits of greenroofs are discussed in more
Increased Roof Longevity
Greenroofs in Europe have easily lasted from 40 to 75 years, or even
much longer. Common theory holds that roof life can be at least doubled, and
perhaps tripled or more, with a greenroof. The main reason for this is that the
multiple layers protect the waterproofing membrane and structural elements from
damaging ultraviolet rays, wind, and temperature fluctuation extremes.
In Europe, Japan, and North America, major greenroof providers will issue
at least a 20-year assembly warranty and performance guarantee. In Germany,
direct greenroof subsidies are available in about 30 cities. They range from
$0.51 to $6.20 per square foot, based on avoided maintenance and replacement
Reduced Energy Consumption and Costs
Thermally insulating greenroofs offer energy savings. Benefits vary by
geographic region and type of system, but it is agreed that they can reduce peak
energy demand by lowering cooling and heating needs, at least for the floor
directly below the greenroof.
Some experts argue that some published energy reports have been
exaggerated. They nevertheless agree it is impossible to issue blanket
statements regarding energy savings for every region of the world, since many
factors contribute to the figures. When estimating energy savings, it is essential
to study each climate individually, using thermodynamic data.
That said, in December 2000, Weston Solutions design consultants
conducted an energy study for the City of Chicago which estimated that it would
be possible to save $100,000,000 in avoided energy costs annually with the
greening of all the city's rooftops. The study's bottom line stated that "[p]eak
demand would be cut by 720 megawatts -- the equivalent energy consumption of
several coal-fired generating stations or one small nuclear power plant.” Weston
also declared that, in general, reductions of up to 50 percent of cooling costs and
25 percent of heating costs could be achieved, at least for the floor directly below
A 2003 study commissioned by Seattle's Office of Sustainability and the
Environment states that the Seattle Justice Center is saving as much as
$148,000 each year due to its greenroof.11
Understanding how heat moves through a greenroof can be tricky,
however. Engineer and energy modeler Chris Wark of Green Roof Innovations
Energy usage is reduced primarily due to the solar heat
management of the foliage and thermal mass of the soil substrate
(not the plants). Plant leaves transfer nearly all excess solar
energy to the surrounding air and absorb the rest, while the soil
mass provides an additional benefit of dampening temperature
fluctuations. Leaf transpiration is one of the ways in which the solar
heat is transferred to the air. If enough water is available,
additional heat can be removed from the plant, but this is a minor
effect with succulents. The fact that leaf temperatures of many
different studied plants tends toward ambient air temperatures
proves this. In most cases, a green roof comes with a heating
penalty if any moisture is at all retained in the soil (and it is).
Chris and Wendy Wark have reported results from a study done on
commercial buildings in Northern California using DOE-212 and a proprietary roof
heat transfer model developed by their parent company, Shade Consulting.
Their study indicated that an uninsulated greenroof could reduce the building
heating/cooling system's demand for most of the year by 30 percent over a
conventional dark roof with R-18 rigid insulation and without a radiation barrier.13
Increased Developable Space
Major cities that are embracing sustainable design have acknowledged
the economic benefits of greenroofs and are helping to pass the savings they
generate along to owners and builders. For example, city officials may reduce
impervious coverage requirements for developers who incorporate greenroofs
into their site plans.
Depending on local ordinances and applicable BMPs, officials may allow
greenroofs to be installed in lieu of conventional stormwater management
elements. Greenroofs can significantly reduce the required size of unsightly,
space-wasting, and expensive retention ponds or underground galleries, or even
completely eliminate the need for these elements.
In some cities, floor-to-area development ratios can also be increased. In
Portland, Oregon, for example, builders can now increase their floor area ratio
(FAR) when they include a greenroof that covers at least 60 percent of the roof
surface. This FAR bonus grants an additional three square feet of floor area per
square foot of greenroof, to be added to the footprint of the building.
The City of Chicago also increases development square footage, known
as floor area premiums, when developments include public amenities such as
Reduced Local Impact Fees and Increased Incentives
Reduced stormwater and impervious cover fees, as well as energy credits,
grants, and tax incentives for greenroofs, have been in place in European
countries such as Germany, the Netherlands, Switzerland, and Sweden for
decades. For example, some German municipalities offer stormwater fee
reductions of 50 to 80 percent.
Cities in the United States and Canada are now beginning to offer
incentives as well. Portland, Oregon plans to reduce stormwater utility fees for
buildings with greenroofs by July 2006. The City's Clean River Incentive and
Discount Program promotes placement of ecoroofs atop commercial, industrial,
institutional, multi-family, and single family residential properties.
New York, Seattle, Chicago, Toronto, Vancouver, St. Paul, Atlanta, and
several cities around Washington, D.C., are among those working toward
reducing various fees in exchange for greenroof development.
Greenroofs as Stormwater Mitigation Measures
Greenroofs can sometimes be used as stormwater mitigation measures.
In Portland, Oregon, all building projects that will result in at least 500 square feet
(46 square meters) of impervious surface are required to implement stormwater
pollution reduction and flow control measures. Greenroofs are recognized as
one of the acceptable approaches to meeting this requirement.14
Greenroofs as Heat Island Measures
In a concerted effort to combat the ever-increasing urban heat island
effect in Tokyo, the city's "Tokyo Plan 2000" was implemented on April 1, 2001.
It requires new buildings that are larger than 1,000 square meters (10,000 square
feet), or over one-quarter acre, to green at least 20 percent of their useable roof
Other countries considering these types of measures include South Korea
and Singapore. In the U.S., cities like New York would also greatly benefit from
Increased Points in the LEED™ Rating System
The U.S. Green Building Council (USGBC) has developed and oversees
the LEED (Leadership in Energy and Environmental Design) Green Building
Rating System®, a voluntary, consensus-based national standard for developing
high-performance, sustainable buildings. The four levels of certification include
LEED™ Certified, Silver Level, Gold Level, and Platinum Level. Greenroofs
qualify for at least six points in three categories, and more points are possible
under specific conditions.
Many local, state, and federal agencies have adopted sustainable design
stipulations that adhere to LEED™ principles. For example, in 2000, the City of
Seattle adopted its Sustainable Building Policy, which requires many new city
buildings to attain a Silver LEED™ certification rating. The requirement applies
to new and renovated city facilities that are larger than 5,000 square feet.
The General Services Administration (GSA), a federal agency, requires
buildings to be certified through LEED™, and encourages them to achieve a
Silver LEED. EPA requires Silver LEED™ certification for new significant
building construction or acquisition. NASA encourages its designers to strive for
a LEED™ Gold rating, if cost effective.15
Increased Building Marketability
High-rise apartments, office space, and even hotel rooms with the
enhanced natural view afforded by greenroofs can support higher rents or room
rates and help maintain increased levels of occupancy. Resale prices also
increase with the added value of additional greenspace.
Emerging Synergy with Solar Power
Greenroofs can be successfully combined with solar power projects. In
Germany, construction of such combined projects has generated significant
Studies show that the cooler temperatures found on a greenroof enhance
the performance of photovoltaics, while the greenroof buildup provides a steady
base for solar installations.
Combining greenroofs with solar power not only will capitalize on the
technologies' energy use reduction potential, but also will help create a
renewable energy source -- all without utilizing more land.16
The restoration and revitalization of our cities should include adapting
exterior architecture to meet the desires of communities. Few people would deny
that urban areas are enhanced with the natural beauty and soothing aesthetics of
The sections that follow briefly detail some of the aesthetic benefits of
Commercial and industrial roofs no longer need to be unattractive, harsh
eyesores. With the addition of greenroofs, we can create pleasing, vigorous,
sustainable native and naturalized plant communities.
Integration into Natural Surroundings
Greenroofs can help buildings blend unobtrusively into suburban areas or
the open countryside. Overhead views could actually be camouflaged if the
planting design mimicked its surroundings.
Varied Design Possibilities
Greenroofs can be designed in many different forms, and can be used on
sloped or flat roofs. Some owners might want naturalistic landscapes that
resemble meadows planted with wildflower drifts. Others might prefer wildly
Recreating natural landscapes through greenroofs can create beauty that
is soothing to our psyches. And in utilizing greenroofs, we also accomplish many
other objectives that help fulfill our need for purpose.
Through greenroofing, we nurture the built environment and incorporate
the tenets of high-performance building and environmentally preferable design.
We help clean the air and water, and promote energy efficiency. We create
ecologically sustainable sites. We make better use of cultural and natural
resources and materials.
Some of the key psychological benefits of greenroofs are highlighted in
the sections that follow.
Appealing to Biophilia
A connection to nature appears to be a part of our evolutionary heritage --
a concept that sometimes is called "biophilia."
Perhaps because of this connection, being able to view and experience
nature is excellent for our mental heath. Therapeutic roof gardens are becoming
popular in hospitals, care centers, and similar settings. Experiencing the change
of seasons is life-reassuring.
Frederick Law Olmstead, who is recognized as the founder of American
landscape architecture, once said, "Humans have physiological reactions to
natural beauty and diversity, to the shapes and colors of nature, especially to
green, and to the motions and sounds of other animals."17
Making Employees Happier
If you were working in a typical stark office environment, what would you
rather look down onto -- a natural scene (such as a flowing riverscape or
flowering meadow) or a dreary grey and black expanse of roofs?
Clearly, greenroofs have the potential to make workers happier by
enhancing their surroundings. This in turn could improve business profitability
since it has been theorized that enhancing the emotional or physical comfort of
employees can increase productivity and lower absenteeism.
Greenroofs help visually ease the stress created by the lack of
greenspace in urban buildings. Natural views reduce aggression and increase
Fostering a Sense of Community
Greenroofs can create sustainable interactive community spaces where
people can garden, visit, play, and relax together. They also offer opportunities
for educating the public through displays and interpretive signage describing the
greenroof design process.
With greenroofs, we can make the decision to design with nature, instead
of against her. Greenroofs can help mitigate some of our most pressing urban
development issues, while also allowing us to reap economic benefits through
reducing various building-associated costs and promoting a growing design and
construction industry. Organic greenroof architecture can actually help restore
the health of Earth’s ecology.
In a followup article that will appear in a future issue of this journal, I plan
to offer more detail on greenroof design and related issues.
Linda S. Velazquez, ASLA Associate, LEED AP, holds a Bachelor's of
Landscape Architecture (cum laude) from the University of Georgia. She is
founder and publisher of Greenroofs.com, the international greenroof industry's
resource and online information portal, and publisher of The Greenroof Directory
of Manufacturers, Suppliers, Professional Services, Organizations & Green
Resources. Greenroofs.com serves as a clearinghouse and reference resource
for articles, upcoming events, and organizations, and includes the global
Greenroof Projects Database, a free online resource. Greenroofs.com is listed
by the USGBC's LEED Green Building System as the website resource for green,
or vegetated, roofs. Ms Velazquez is a LEED Accredited Professional who
designs, consults, and presents on greenroofs nationally and internationally. She
has written and reported extensively about greenroofs, including her bi-monthly
column entitled "Sky Gardens -- Travels in Landscape Architecture" on
Greenroofs.com. For more information, see www.greenroofs.com.
Office of the Federal Environmental Executive (2003,
September). The Federal Commitment to Green Building:
Experiences and Expectations. Available at
Unless otherwise noted, all information cited in this
article comes from either Greenroofs.com or the research of
Linda S. Velazquez.
U.S. Census Bureau (2004, March). Global Population at a
Glance: 2002 and Beyond. Available at
Data on resource consumption, fossil fuel use, and species
depletion comes from The World Wildlife Fund's 2004 Living
Planet Report. Available at
English Nature (2003). Green Roofs: Their Existing
Status and Potential for Conserving Biodiversity in Urban
Areas. English Nature Research Report Number 498.
Available at http://www.english-
Wark, C.G., & Wark, W.W. (2003, August). Green Roof
Specifications and Standards. The Construction Specifier,
56(8). Available at
Johnston, J., & Newton, J. (1993). Building Green: A
Guide to Using Plants on Roofs, Walls and Pavements.
London: London Ecology Unit.
National Research Council Canada Press Release (2002,
October 9). Government of Canada Reveals Major Greenhouse
Gas Reductions and Air Quality Benefits from Widespread Use
of "GreenRoofs." Available at http://www.nrc-
Duffy, K. (2004, April 18). NASA Studies How to Cool Area
as Heat Builds Up. Atlanta Journal Constitution.
Urban Heat Island Initiative Pilot Project: Final Report
(2000, May 9). Prepared for the City of Chicago by Roy F.
Weston, Inc. (now Weston Solutions, Inc).
Steinbrueck, P. (2005, January 13). Putting a Green Cap
Atop the Emerald City. The Seattle Times. Available at
DOE-2 calculates the hourly energy use and energy cost of
a commercial or residential building based on information
about the building’s climate, construction, operation, and
utility rate schedule, and its heating, ventilating, and
air-conditioning (HVAC) equipment.
Chris Wark, personal communication, November 2004.
Environmental Building News, 10(11).
Office of the Federal Environmental Executive (2003,
September). The Federal Commitment to Green Building:
Experiences and Expectations. Available at
Alt, F. (2004, September 14). Future Oriented
Technologies: Green Roofs and Solar Power. Presentation
at the International Green Roof Congress 2004.
Quoted in Dramstad, W.E., Olson, J.D., & Forman, R.T.T.
(1996). Landscape Ecology Principles in Landscape
Architecture and Land-Use Planning, Cambridge,
Massachusetts: Harvard University Graduate School of
Tuesday, October 30, 2007
The state tree of North Dakota. A large vase-shaped tree
adapted to a wide variety of sites. No longer recom-
mended because of its susceptibility to Dutch Elm Disease.
The largest tree in North Dakota is 62 feet tall with a
canopy spread of 74 feet.
Leaves and Buds
Bud Arrangement - Alternate.
Bud Color - Smooth, sharp-pointed, and reddish-brown.
Bud Size - Lateral buds are small, 1/4 inch long.
Leaf Type and Shape - Simple, unequal at the base,
Leaf Margins - Doubly-serrate.
Leaf Surface - Glabrous to rough above, pubescent or
nearly glabrous beneath.
Leaf Length - 3 to 6 inches.
Leaf Width - 2 to 3 inches.
Leaf Color - Dark-green above, lighter green below; Yello Fall Collor
Flowers and Fruits
Flower Type - Polygamo-monoecious, in fascicles of 3 or 4.
Flower Color - Greenish-red to brownish.
Fruit Type - Winged samara, oval-globose and wafer-like
in appearance, notched.
Fruit Color - Light-green, changing to tan.
Growth Habit - Trunk divides into several erect arching
limbs above, umbrella to vase-shaped.
Texture - Medium-coarse, summer; medium-coarse,
Crown Height - 45 to 65 feet.
Crown Width - 30 to 50 feet.
Bark Color - Dark gray-brown, with broad ridges and
Root System - Root spread is greater than height. Root
system is shallow, fibrous, and in dry areas may have a tap
Soil Texture - Grows best in rich, moist, well-drained soils,
but adapts to a wide range of soil types.
Soil pH - 5.5 to 8.0.
Windbreak Suitability Group - 1, 1K, 3, 4, 4C, 5.
USDA Zone 2.
Drought tolerant, but prolonged drought stress predis-
poses trees to pests. Tolerant of infrequent, short duration
flooding during the growing season.
Full sun to partial shade.
Tall tree for farmstead and field windbreaks, and riparian
Seed, buds, and tender young twigs are used as food by
birds and mammals, particularly deer.
Wood - Used in fine furniture, boxes, barrels, and crates.
Good for firewood, but hard to split.
Medicinal - Extracts of some Ulmus species have been used
as a demulcent, an astringent, a diuretic, and for inflam-
mation, burns, cold sores and wound treatments.
A favorite tree for all sites, but no longer recommended
because of Dutch Elm Disease.
Ulmus americana ‘Ascendens’ and ‘Augustine’ - Cultivars
with columnar form.
U. americana ‘Lake City’, ‘Moline’, and ‘Minneapolis Park’
- Variably vase-shaped. Due to susceptibility to Dutch Elm
disease, the above cultivars are rarely planted (see
Japanese Elm and Siberian Elm for Dutch Elm disease
David Elm (U. davidiana)
European White Elm (Ulmus laevis)
Japanese Elm (U. davidiana var. japonica)
Lincoln Elm (U. rubra ‘Lincoln’)
Rock Elm (U. thomasii)
Slippery Elm (U. rubra)
Besides Dutch Elm disease, common diseases include
wetwood, black leaf spot, and branch cankers. Common
insect pests include cankerworms and aphids. Deer
browse damage can be serious on young trees.
Monday, October 29, 2007
Genus: Viburnum (vy-BUR-num) (Info)
Species: lantana (lan-TAN-uh) (Info)
12-15 ft. (3.6-4.7 m)
12-15 ft. (3.6-4.7 m)
USDA Zone 3a: to -39.9 °C (-40 °F)
USDA Zone 3b: to -37.2 °C (-35 °F)
USDA Zone 4a: to -34.4 °C (-30 °F)
USDA Zone 4b: to -31.6 °C (-25 °F)
USDA Zone 5a: to -28.8 °C (-20 °F)
USDA Zone 5b: to -26.1 °C (-15 °F)
USDA Zone 6a: to -23.3 °C (-10 °F)
USDA Zone 6b: to -20.5 °C (-5 °F)
USDA Zone 7a: to -17.7 °C (0 °F)
USDA Zone 7b: to -14.9 °C (5 °F)
Sun to Partial Shade
Parts of plant are poisonous if ingested
Late Spring/Early Summer
Average Water Needs; Water regularly; do not overwater
This plant is attractive to bees, butterflies and/or birds
Soil pH requirements:
5.6 to 6.0 (acidic)
6.1 to 6.5 (mildly acidic)
6.6 to 7.5 (neutral)
From softwood cuttings
From semi-hardwood cuttings
N/A: plant does not set seed, flowers are sterile, or plants will not come true from seed
Saturday, October 27, 2007
Family: Ulmaceae (ulm-AY-see-ay) (Info)
Genus: Ulmus (ULM-us) (Info)
Species: glabra (GLAY-bruh) (Info)
Height: 20-30 ft. (6-9 m)
Spacing: 30-40 ft. (9-12 m)
USDA Zone 4a: to -34.4 °C (-30 °F)
USDA Zone 4b: to -31.6 °C (-25 °F)
USDA Zone 5a: to -28.8 °C (-20 °F)
USDA Zone 5b: to -26.1 °C (-15 °F)
USDA Zone 6a: to -23.3 °C (-10 °F)
USDA Zone 6b: to -20.5 °C (-5 °F)
USDA Zone 7a: to -17.7 °C (0 °F)
USDA Zone 7b: to -14.9 °C (5 °F)
USDA Zone 8a: to -12.2 °C (10 °F)
USDA Zone 8b: to -9.4 °C (15 °F)
Sun Exposure: Sun to Partial Shade
Bloom Color: NA
Soil pH requirements:
Friday, October 26, 2007
Sun -sun/part sun
Height -25.0 ft
Width - 20.0 ft
Water - average
Growth rate - average
Hardiness Zones 5-8
Soil - well drained soils
Flower - white bracts
Seed - fleshy red fruits
Foliage - Deciduous
Fall Color- reddish purple
Offspring of Cornus kousa 'Milky Way', a proven northern performer.
Trial plantings have proven their hardiness rating equal to native species Cornus florida.
Attractive creamy-white and green variegated foliage is highlighted with rich pink hues in late summer and fall.
Prolific bloomer in May and June, after the majority of spring flowering ornamentals have finished blooming.
Ideal replacement for disease stricken native dogwood Cornus florida.
A Care Free Maintenance™ tree, requiring little or no maintenance to maintain its natural form and beauty.
Striking ornamental tree for featuring in commercial and residential landscapes.
Understory tree in large naturalized plantings.
Ideal alternate for Cornus florida and Cornus kousa and cultivars.
Prefers moist, acidic, well drained soils with high organic content, pH 4.5-6.5.
Plant in full sun or partial shade.
Best planted in the spring.
Rate of Growth: Moderate, faster than species.
current lcn production
No.5 and No.7 Container.
Click here for current availability.
Propagate by summer mist cuttings (root readily) or budding.
Foliage does not scorch in the hot sun.
Reports from industry indicate Samaritan® is the best variegated kousa dogwood being grown to da
Thursday, October 25, 2007
Pyrus calleryana ‘Redspire’
‘Redspire’ Callery Pear quickly grows 35 to 45
feet high and 20 feet wide, with upright-spreading,
thornless branches (Fig. 1). The narrow crown enable
this tree to be used in tight overhead spaces. The
silhouette appears as a fat column growing wider than
‘Whitehouse’ and ‘Capital’ but narrower than
‘Bradford’ and ‘Aristocrat’. In spring before the new
leaves unfold, the tree puts on a nice display of pure
white flowers larger than ‘Bradford’ or ‘Aristocrat’.
Flowering may be subdued in USDA hardiness zone
8b and it occurs at about the same time as ‘Bradford’
Callery Pear. The leaves emerge as red/purple, then
become 1.5 to 3 inches long, glossy green with wavy
margins and a red blush. They turn yellow to orange
in fall in the south putting on an attractive display
before dropping. Fall color may be subdued in the
north. The small, pea-sized, red/brown fruits which
form are quite attractive to birds and other wildlife,
and mummify on the tree persisting for several months
to a year. Planting two or more cultivars of Callery
Pear together could increase fruit set.
Scientific name: Pyrus calleryana ‘Redspire’
Pronunciation: PIE-rus kal-ler-ee-AY-nuh
Common name(s): ‘Redspire’ Callery Pear
USDA hardiness zones: 5 through 9A (Fig. 2)
Origin: not native to North America
Uses: container or above-ground planter; large
parking lot islands (> 200 square feet in size); wide
tree lawns (>6 feet wide); medium-sized parking lot
islands (100-200 square feet in size); medium-sized
tree lawns (4-6 feet wide); recommended for buffer
strips around parking lots or for median strip plantings
in the highway; screen; shade tree; small parking lot
islands (< 100 square feet in size); narrow tree lawns
(3-4 feet wide); specimen; sidewalk cutout (tree pit);
residential street tree; tree has been successfully grown
in urban areas where air pollution, poor drainage,
Height: 35 to 45 feet
Spread: 20 to 30 feet
Crown uniformity: symmetrical canopy with a
regular (or smooth) outline, and individuals have more
or less identical crown forms
Crown shape: pyramidal
Crown density: moderate
Growth rate: fast
Leaf arrangement: alternate (Fig. 3)
Leaf type: simple
Leaf margin: crenate; sinuate; undulate
Leaf shape: ovate
Leaf venation: pinnate; reticulate
Leaf type and persistence: deciduous
Leaf blade length: 2 to 4 inches; less than 2 inches
Leaf color: green
Flower color: white
Flower characteristics: spring flowering; very
Fruit shape: round
Fruit length: < .5 inch
Fruit covering: dry or hard
Fruit color: brown; tan
Fruit characteristics: attracts birds; attracts squirrels
and other mammals; inconspicuous and not showy; no
significant litter problem; persistent on the tree
Trunk and Branches
Trunk/bark/branches: bark is thin and easily
damaged from mechanical impact; routinely grown
with, or trainable to be grown with, multiple trunks;
grow mostly upright and will not droop; not
particularly showy; tree wants to grow with several
Tuesday, September 25, 2007
Family: Cornaceae (Nyssaceae)
Species: N. sylvatica
Binomial name Nyssa sylvatica
Black Tupelo (Nyssa sylvatica), is a medium-sized deciduous tree which grows around 20-25 m (65-80 ft) tall (rarely to 35 m) and a trunk diameter of 50-100 cm (20-40 in) (rarely up to 170 cm). It is native to eastern North America, from New England and southern Ontario south to central Florida and eastern Texas.
The species is often known as simply Tupelo, but the full name Black Tupelo helps distinguish it from the other species of tupelo, some of which (Water Tupelo N. aquatica and Swamp Tupelo N. biflora) occur in the same area. The name Tupelo is of Native American origin. Other names include Blackgum, Pepperidge, Sourgum, and (on Martha's Vineyard) Beetlebung, this last perhaps from the mallet known as a beetle, used for hammering bungs, or stoppers, into barrels ("Beetlebung" and other tupelo lore). The scientific name means "nymph of the woods" in Greek.
The leaf of Black Tupelo is variable in size and shape. It can be oval, elliptical or obovate, and 5-12 cm (2-5 in) long. It is lustrous, with entire, often wavy margins. The leaf turns purple in autumn, eventually becoming an intense bright scarlet. The flower is very small, greenish-white in clusters at the top of a long stalk. The fruit is a black-blue, ovoid stone fruit, about 10 mm long with a thin, oily, bitter-to-sour flesh. There are from one to three such fruit together on a long slender stalk. The bark is dark grey and flaky when young, but it becomes furrowed with age, resembling alligator hide on very old stems. The twigs of this tree are reddish-brown, usually hidden by a greyish skin. The pith is chambered with greenish partitions. The branches typically stand at right angles to the trunk.
∑ Bark: Light reddish brown, deeply furrowed and scaly. Branchlets at first pale green to orange, sometimes smooth, often downy, later dark brown.
∑ Wood: Pale yellow, sapwood white; heavy, strong, very tough, hard to split, not durable in contact with the soil. Used for turnery. Sp. gr., 0.6353; weight of cu. ft., 39.59.
∑ Winter buds: Dark red, obtuse, one-fourth of an inch long. Inner scales enlarge with the growing shoot, becoming red before they fall.
∑ Leaves: Alternate, often crowded at the end of the lateral branches, simple, linear, oblong to oval, two to five inches long, one-half to three inches broad, wedge-shaped or rounded at base, entire, with margin slightly thickened, acute or acuminate. They come out of the bud conduplicate, coated beneath with rusty tomentum, when full grown are thick, dark green, very shining above, pale and often hairy beneath. Feather-veined, midrib and primary veins prominent beneath. In autumn they turn bright scarlet, or yellow and scarlet. Petioles one-quarter to one-half an inch long, slender or stout, terete or margined, often red.
∑ Flowers: May, June, when leaves are half grown. Polygamodiœcious, yellowish green, borne on slender downy peduncles. Staminate in many-flowered heads; pistillate in two to several flowered clusters.
∑ Calyx: Cup-shaped, five-toothed.
∑ Corolla: Petals five, imbricate in bud, yellow green, ovate, thick, slightly spreading, inserted on the margin of the conspicuous disk.
∑ Stamens: Five to twelve. In staminate flowers exserted, in pistillate short, often wanting.
∑ Pistil: Ovary inferior, one to two-celled; style stout, exserted, reflexed above the middle. Entirely wanting in sterile flower. Ovules, one in each cell.
∑ Fruit: Fleshy drupe, one to three from each flower cluster. Ovoid, two-thirds of an inch long, dark blue, acid. Stone more or less ridged. October.
The Black Tupelo (Nyssa Sylvatica) grows best in well drained areas. Nyssa Aquatica grows best in swamps or lowlands that have poor drainage. Usually reaches the height of fifty feet and occasionally one hundred; variable in form. Roots are large, striking deep.
The limbs deteriorate early and the decayed holes make excellent dens for squirrels, raccoons, opossums and honeybees. Hollow sections of trunk were formerly used as bee gums by beekeepers.
The glossy beauty of the Tupelo is undoubtely the reason why it so often is permitted to escape the levelling axe and allowed to stand in the fields with the elm, oak, and maple. In such a situation its contour is as individual as that of any of its companions. The stem rises to the summit fo the tree in one tapering unbroken shaft, the branches come out at right angles to the trunk and either extend horizontally or droop a little, making a long-narrow, cone-like head. The spray is fine and abundant and lies horizontally so that the foliage arrangement is not unlike that of the beech. The leaves are short petioled and so have little individual motion, but the branch sways as a whole.
The tree rarely flourishes in exposed positions, it dies at the top and lives on in a half-hearted way until the friendly axe ends the unequal struggle. But, allowed to grow in freedom, sheltered but not crowded, it develops a full round head and lives to good old age.
The flowers are inconspicuous, but the fruit is quite marked, dark blue, in clusters of two or three, sour but eagerly sought by the birds.
Its autumnal coloring is superb; the foliage becomes one glowing mass of scarlet, sometimes dashed with orange. It is the most fiery and brilliant of all that brilliant group: the maple, dogwood, sassafras, liquidambar, and tupelo.
The wood is hard, cross-grained, and difficult to split, especially after drying. It is used for pallets, rough floors, pulpwood and firewood. It is also grown as an ornamental tree in parks and large gardens, with its often spectacular intense red to purple fall color being highly valued.
The Black Tupelo is an important food source for many migrating birds in the fall. It's early color change (foliar fruit flagging) is thought to attract birds to the available fruit, which ripen before many other fall fruits and berries.
Birds recorded to feed on the fruit include: American Robin, Swainson's Thrush, Gray-cheeked Thrush, Hermit Thrush, Wood Thrush, Northern Cardinal, Northern Mockingbird, Blue Jay, Red-bellied Woodpecker, Yellow-bellied Sapsucker, Northern Flicker, Pileated Woodpecker, Eastern Phoebe, Brown Thrasher, Eastern Bluebird, European Starling, Scarlet Tanager, Gray Catbird, Cedar Waxwing, and American Crow, all primarily eastern birds migrating or residing year-round within the tree's range.
Thursday, September 20, 2007
Family: Rosaceae (ro-ZAY-see-ay) (Info)
Genus: Crataegus (krah-TEE-gus) (Info)
Species: crus-galli var. inermis
Height:_15-20 ft. (4.7-6 m)
Spacing:_15-20 ft. (4.7-6 m)
Hardiness:_USDA Zone 4a: to -34.4 °C (-30 °F)_USDA Zone 4b: to -31.6 °C (-25 °F)_USDA Zone 5a: to -28.8 °C (-20 °F)_USDA Zone 5b: to -26.1 °C (-15 °F)_USDA Zone 6a: to -23.3 °C (-10 °F)_USDA Zone 6b: to -20.5 °C (-5 °F)_USDA Zone 7a: to -17.7 °C (0 °F)_USDA Zone 7b: to -14.9 °C (5 °F)
Sun Exposure:_Full Sun_Sun to Partial Shade
Danger:_Seed is poisonous if ingested
Bloom Color:_White/Near White
Bloom Time:_Late Spring/Early Summer
Other details:_This plant is attractive to bees, butterflies and/or birds_Drought-tolerant; suitable for xeriscaping_Average Water Needs; Water regularly; do not overwater
Soil pH requirements:_6.1 to 6.5 (mildly acidic)_6.6 to 7.5 (neutral)_7.6 to 7.8 (mildly alkaline)
Propagation Methods:_From woody stem cuttings_From seed; direct sow outdoors in fall_From seed; stratify if sowing indoors
Seed Collecting:_Collect seedhead/pod when flowers fade; allow to dry
Monday, September 17, 2007
Sunburst Honey Locust
Gleditsia triacanthos f. inermis 'Sunburst'
The Sunburst Honeylocust tree, Gleditsia triacanthos inermis, 'Sunburst', is smaller in stature than the common Honeylocust tree. Sunburst Honeylocust trees display yellow new growth, and the yellow leaves persists throughout the season. The wood is dense, hard, and durable. The Sunburst Honeylocust is fast growing up to 2 ‘ a year. It is a very fine textured tree with a broad, pyramidal crown, and an excellent lawn tree for filtered shade.
This deciduous tree displays clusters of yellow-green, fragrant flowers open in May-June. The leaves are divided into many small, oval leaflets giving a fern-like appearance to the foliage; leaves are normally green, but the 'Sunburst' cultivar has light yellow leaves. This tree is a version of improved thornless, podless varieties. Easy to transplant because it withstands a wide range of conditions. Does best in moist bottomlands or soils with high pH. Prefers full sun. Extremely salt tolerant.
Saturday, August 25, 2007
Reseeding Bare Spots in Lawns
Lawns often have areas of thin grass or bare spots, which detract from the overall appearance. In most cases, the rest of the lawn is in good condition, and the homeowner doesn't want to tear it out and start over again. Provided there are no major external causes for the bare spots or thin areas, they can usually be easily repaired by reseeding.
Many people attempt to correct bare and thin patches merely by scattering seed over the spots. This is a waste of time and money. Follow these guidelines to reseed bare spots.
Grass Establishment on Problem Areas:
• First, clip the lawn low to get rid of as much existing vegetation as possible.
• Remove dead grass and leaves near the soil surface with a rake. The soil surface should be completely exposed.
• Fill low spots with good soil if necessary.
• Loosen the soil already present in bare spots.
Once you have exposed and loosened the soil, you can seed the spot. Pack or firm the soil lightly after seeding, and continue to clip low, until the new grass establishes itself. Keep the newly seeded areas moist until the grass is up. Weed-free straw or hay mulch helps conserve moisture.
August 15 to September 15, is an excellent time of year to seed lawn grasses.
Introducing lower maintenance turf varieties into an existing lawn can be done through some type of overseeding practice. Selecting grass varieties adaptable to lower input levels is the first important step in making the transition to a lawn adaptable to lower inputs.
Thursday, June 21, 2007
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Monday, May 7, 2007
Family: Rosaceae (ro-ZAY-see-ay) (Info)
Genus: Rosa (RO-zuh) (Info)
Cultivar: New Dawn
Additional cultivar information: (aka Everblooming Dr. W. Van Fleet, The New Dawn)
Hybridized by Somerset 1930
8-10 ft. (2.4-3 m)
10-12 ft. (3-3.6 m)
12-15 ft. (3.6-4.7 m)
15-20 ft. (4.7-6 m)
4-6 ft. (1.2-1.8 m)
6-8 ft. (1.8-2.4 m)
USDA Zone 5a: to -28.8° C (-20° F)
USDA Zone 5b: to -26.1° C (-15° F)
USDA Zone 6a: to -23.3° C (-10° F)
USDA Zone 6b: to -20.5° C (-5° F)
USDA Zone 7a: to -17.7° C (0° F)
USDA Zone 7b: to -14.9° C (5° F)
USDA Zone 8a: to -12.2° C (10° F)
USDA Zone 8b: to -9.4° C (15° F)
USDA Zone 9a: to -6.6° C (20° F)
USDA Zone 9b: to -3.8° C (25° F)
Light pink (lp)
Trained to climb
Trained as rambler
Resistant to black spot
Resistant to mildew
Resistant to rust
Blooms on old wood; prune after flowering
Soil pH requirements:
6.6 to 7.5 (neutral)
From hardwood cuttings