Sustainable Horticulture

What Is Sustainable Horticulture?

Posted by sustainable_hort on March 24, 2010  |  No Comments

This is a quick thank you to all that have checked this blog and made so many positive comments. And more…a short view of where we are headed.

This blog was started to document, explain, revise, suggest and predict where the wide world of horticulture can honestly to create systems to grow plants that do not depend on petroleum based inputs (which at some point become scarce or at least much more expensive), but finds closed systems to supply those inputs. No one is saying it is easy, it still needs work and research, but natural systems are being identified. We just need to rethink some obvious biology, especially relating to soil, and how it has worked “sustainably” for millions of years.

Definitions are tricky…and “sustainability” is seems to be the rule in this case. There are many definitions, the majority of which tend to be bent to service those defining it. But, after reading numerous definitions, it seems to boil down creating ways to grow plants that will without harming workers or future generations later. Many include the definition of “environmental health, economic profitability, and social and economic equity.” This must mean “we must meet the needs of the present without compromising the ability of future generations to meet their own needs.” So, “stewardship” requires “maintaining or enhancing this vital resource base (soils, water and closed inputs) forever.”

Certain food and ornamental products have identified with this “sustainable” vision. More than identified, they have built businesses, created organic fertilizers and pesticides, established networks and distribution systems that are a first stage in creating a more sustainable horticulture. It might even lead to a more sustainable agriculture…a different conversation.

Even Miracle Grow, not the most organic product in the world, is now selling two soil amendment products. These miracle products, which the company promotes as containing “organic” components, promise healthy soils that “grow plants twice as large.” The company has recognized the concept, along with much of agriculture, that healthy soil is the literal and environmental foundation of sustainable horticulture, whether in farms or landscapes.

So, this blog first focuses on ornamental plant production. I am working with a wholesale grower in the wonderful Willamette Valley, Oregon, where plants like to grow. It is one of the main reasons I live here today. We are seeing if a grower of shrubs and trees can work towards a sustainable sustainability…one that works economically long term. A key phrase in this sentence is “long term.” And it may mean growing not the largest plant, but the healthiest plant. This is not just speculation, but has a background, starting with the works of Sir Alfred Howard and William Albrecht, and continuing today with the Rodale organization, the Leopold Center for Sustainable Agriculture, and ATTRA. I suggest reading New Opportunities in Sustainable Landscapes and Can Nurseries be Sustainable? on this blog, and investigating the references. Let’s keep the discussion going.

At the same time, this site will point to new uses of plants from green roofs and walls, to storm water control with green streets, to growing food on empty rooftops and in our neighborhoods. We find cities planting more trees, urban agriculture sneaking into backyards and along cities edges, plants being used to clean water and air, and cool our heat islands. This is all positive and needs to be recognized as an important environmental strategy, one that can also create jobs. Obviously, without plants, there is no food or air, there is no “us.” So, it becomes important to recognize and utilize plants at every level we can.

Finally, this discussion site will lead to the introduction and testing of organic input products here in the Northwest (with application nationally), and we will be providing some of those products through this site and with advertising support. This all works toward my focus, helping horticultural growers (both food and ornamental) move, step by step, to a sustainable future while still providing the planet with plants.

And, a main test site will be our organic produce operation, 19th Street Farms. Since the links on this template are not working right, just type in “www.19thstreetfarms.com/blog/” to get to the site. I will use this blog for other content, but the site will busy in summer. It is also our CAS/Farmers Market site where we are continually talking with our customers. So look under specific categories for your favorite topic.

MORE COMING SOON…

Green Streets/Bioswales/Rain Gardens

Posted by sustainable_hort on March 16, 2010  |  No Comments

After at least a century of hard engineering solutions for urban rain/storm water run-off, communities are turning more and more to using a plant-based technology that mimics nature’s wetlands and ponds.

Portland, Oregon, has played a leading role in supporting and developing this concept, with successful demonstration projects now helping control negative storm water events that included flooding and the overflow of sewage into local rivers.

Just holding back the flow of a major rain event is enough justification for continuing the development of green streets, or rain gardens. When the cost of “hard” infrastructure is considered, these plant-based technologies may be the perfect “green” technology to receive early installation.

All these variations…green streets and rain gardens…are built on the concept of bioswales. So, much of the information is based on bioswale research and the success of earlier projects.

A Decade of Development
One of the first scientifically designed, large-scale bioswales was built in 1996 for Willamette River Park in Portland, Oregon. This bioswale, at a total of 2330 lineal feet, was designed to capture pollutant runoff and prevent it from entering the Willamette River. Silt capture was improved by adding intermittent check dams. The dams reduced suspended solids entering the river system by 50 per cent.

Another example of a large, designed bioswale is at the Carneros Business Park, in Sonoma County, California. In 1997 the California Department of Fish and Game and County of Sonoma, working with an environmental design team, created a detailed design that took the surface runoff from the park’s large parking area. The runoff came from the building’s roof and parking lots. There was also an overland flow from properties located north of the project site. A two-mile bioswale was built to reduce runoff contaminants from entering Sonoma Creek. The grass-lined bioswale channel has an almost linear construction, with a down slope gradient of four percent and six percent cross-slope gradient.

Another early project, completed in 2001, is Seattle’s pilot Street Edge Alternatives Project (SEA Streets). Its drainage designs closely mimics the natural landscape compared to traditional piped systems. Impervious surfaces were reduced, now with 11 percent less than a traditional street while providing improved surface detention in swales. SEA also added over 100 evergreen trees and 1100 shrubs. Two years of monitoring show that SEA Street reduced the total volume of storm water leaving the street by 99 percent.

Meanwhile, back in Portland, the Bureau of Environmental Services has created a “green streets” program. In one project, the city retrofitted SW 12th Avenue, near Portland State University, to collect runoff from 8,000 sq ft and running it into a series of four planters. Up to 6 inches of water can be collected in each planter, then the water overflows down the street to the next planter. In 2006, the project won a General Design Award of Honor from the American Society of Landscape Architects.

There are even companies now that focus on the design, construction and promotion of rain gardens and related products, such as rain barrels. This is another great example of how the low-tech use of plants can solve serious environmental problems, instead of billion dollar “hard” solutions such as Portland’s two massive pipe system projects now under construction.

Definitions
But, despite many similarities, there are some differences between the bioswale variations.

A swale is a low tract of land, that usually exists in a moist or marshy situation and can be a natural landscape feature or one specifically built for environmental reasons. The later is often an open drain system is that manages water runoff.

Bioswales are landscape elements designed and built to remove silt and pollution from surface runoff water. These “swaled” drainage courses are, in a sense, gently sloped ditches that contain plants, compost and/or riprap. The sloped sides are usually less than six percent slope.

As water flows though the typically wide and shallow ditch, so the water spends enough time in the swale, to help trap of silt and pollutants, a bioswale can have a meandering or almost straight channel alignment, based on the lie of the land where it is built.

Bioswales are often built around parking lots due to auto pollution. Potential harmful compound end up being collected on the paving and then flushed by rain. The bioswale, acts as a biofilter, and surrounds the parking lot. As the runoff enters the bioswale, it is cleaned before entering a watershed or storm sewer.
The bioswales can also contain biological factors also contribute to the breakdown of certain pollutants.
Bio-retention ponds, commonly called “rain gardens,” are landscape features that help control rainwater runoff. The runoff comes from roofs, driveways, walkways, compacted lawn areas and other impervious urban surfaces, and cause problems, especially during the large storm events. Structures, low-lying depressions and other landscape constructions that slow and deter running water allow heavy rains to be absorbed into the soil. This prevents the urban situation where the rains flow into storm drains and cause secondary environmental problems. Or it becomes surface water that causes erosion, water pollution, flooding, and diminished groundwater. Some studies claim this can reduce the pollution reaching creeks and streams by up to 30 percent.

Rain garden plants also return water vapor into the atmosphere through the transpiration.

Thus, rain gardens are essentially all landscape features that capture, channel, and divert natural rain and snow that falls on a property. This diverted water may also find other uses, such as stored water returned as irrigation. If designed correctly, an entire landscape or garden can become a rain garden. Individual elements act as components or small-scale rain gardens.

Meanwhile, green streets use small-scale, vegetated bioswales, built along streets that again help control storm water events. These constructed elements create on-site infiltration, while providing attractive streetscapes. They also improve a neighborhood’s livability by adding park-like elements that serve as urban greenways. As mentioned earlier, the City of Portland has officially incorporated green street facilities into all its development, redevelopment or enhancement projects. Besides treating and infiltrating storm water, these projects can also increase tree shade canopy and support native habitat all in the parkways and medians.

It is important to note that these man-made water-control landscapes’ success depends on an adequate “infiltration rate.” This measures, in inches or millimeters per hour, the rate a particular soil absorbs rainfall or irrigation. As the soil becomes saturated, the infiltration rate decreases. When the precipitation rate exceeds the infiltration rate leads to “runoff.” So, the correct soils are also crucial to the overall functioning of all these bioswale variations.

In addition, most of these bioswale-based, water control landscapes are using at least some, if not all, native or related plant choices. This leads to both environmental and cost advantages.

Why Bioswales…Benefits of Water Control Landscapes
These wetland variations, working like their natural versions, have several key benefits that will increase their use as bioswale technology becomes adopted as an effective construction element in urban settings.

• Reduced expense for storm water management facilities
In many locations, natural landscaping, like bioswales or rain gardens, can handle and control storm and flood waters. This, in turn, can reduce the need for expensive, “highly engineered” pipes systems and detention facilities. More and more real world projects are showing that drainage swales can cost much less to install than storm sewers.

“Sustainable innovations can actually reduce costs,” explained landscape architect Paul Morris, speaking at an annual meeting of Oregon Landscape Contractor Association. Morris works on planning and sustainable issues for Cherokee Investment Services, Inc., an international development firm that has long recognized the many benefits of incorporating sustainable technologies into their projects.

He said these include storm water run-off (largest environmental problem in US) control using bioswales, rain gardens, green roofs, and capturing the water on site can be less expensive to construct than traditional solutions.

When curbs and gutters are eliminated and curbs are slotted, there can be substantial construction savings. When natural drainage measures increase infiltration of storm water into the local soil, runoff volume is reduced while the need for downstream conveyance and detention structures is reduced.

Other projects found that detention basins, designed with natural landscaping to resemble wetlands or natural lake systems, also reduce costs over conventional basins. These “natural” landscapes eliminate the need for expensive riprap stabilization and low flow channels paved with concrete. Natural vegetation in detention basin bottoms and on side slopes is less costly to maintain than conventional turf landscaping (see next section), and is a more reliable soil stabilizer.

• Removing Contaminants
As was indicated in the definition of a bioswale, one reason to slow water down is so it can react with the nearby plants, roots and soil. This has documented several benefits.

First, these plant-based technologies can help control several classes of water pollutants, including silt, inorganic contaminants, organic chemicals and pathogens. This falls under the definition (according to Wikipedia) of “biofiltration.” It is defined as “a pollution control technique using living material to capture and biologically degrade process pollutants.” These process include cleaning waste water, capture chemicals that are potentially harmful, micro biotic oxidation of contaminants in air, or collecting silt from surface water runoff.

This is similar to “bioremediation,” which is defined as “any process that uses microorganisms, fungi, green plants or their enzymes to return the natural environment altered by contaminants to its original condition.” Bioremediation may be employed to attack specific soil contaminants, such as degradation of chlorinated hydrocarbons by bacteria. An example of a more general approach is the cleanup of oil spills by the addition of nitrate and/or sulfate fertilizers to facilitate the decomposition of crude oil by indigenous or exogenous bacteria. (Wikipedia)

With silt, the bioswale or rain garden’s effect is to slow the moving water, reducing turbidity, and allowing the small soil particles to drop out of the water. Thus, the soil is returned to a place where it is beneficial instead of traveling downstream to become a problem.

Meanwhile, inorganic compounds, such as metallic compounds like lead, chromium, cadmium and other heavy metals, are common pollutants, especially in areas of heavy auto use. Lead, from automotive residue (e.g. surface spillage of leaded gasoline) is the most common example.

Other common inorganic polluting compounds include phosphates and nitrates, whose main source is excess fertilization. This often causes “eutrophication,” defined as “an increase in chemical nutrients — compounds containing nitrogen or phosphorus — in an ecosystem from the release of sewage effluent, urban storm water run-off, and run-off carrying excess fertilizers into natural waters. It may occur on land or in water.

However, the term is often used to describe the resultant increase, and thus excessive, plant growth and decay in aquatic environments. This results in a lack of oxygen and results in severe reductions in water quality, fish, and other animal populations, disrupting normal functioning of the ecosystem, In aquatic environments, this enhanced growth creates choking aquatic vegetation or phytoplankton, often known as “algal blooms.”

Meanwhile, common pesticides, frequently over-used in agricultural and urban landscaping, are also seriously detrimental organic chemicals. They can actually poison some organisms and often seriously disturb aquatic ecosystems.

Finally, there are human pathogens that usually come from animal waste in surface runoff water. In just the past few years, it has lead to a several serious diseases in humans, with outbreaks coming from spinach and peanut butter.

Less recognized, but still serious, are comparable diseases that have affected aquatic organisms.

• Reduced costs of landscape installation and maintenance
Studies have shown that these “bioremediation” technologies are less expensive than the some other landscaping options. For instance, conventional rolled-sod, turf lawns can have installation costs exceeding $12,000 per acre, while planting grass seeds may cost $4,000 to $8,000 per acre. But, seeding native prairie grasses and forbs costs only $2,000 to $4,000 per acre.
Several publications noted that planting native plants plugs increases installation costs significantly but does give plants a “head start” if desired.

Another plus is that sponsors and volunteers can help control native plant installation costs. Sponsors can even sometimes be a public or private entity with plant propagating capabilities. Volunteers can be recruited to install and maintain native landscapes.

And, natural landscaping just cost less to maintain. Over the first ten years, the combined costs of installation and maintenance for natural landscape can be as little as one fifth of the costs for conventional landscape maintenance. Many projects use a range of native plants already adapted to the region’s soil conditions and climate, including summer heat and drought. Natural landscaping lowers many normal costs including labor, water, fertilizer, herbicides, insecticides, and fungicides, replanting annual flowers, and mowing. In drier climates, natural landscaping lowers the high irrigation costs.

The reduced use of lawn maintenance equipment lowers gas use, an additional benefit. Natural landscapes require simple maintenance, usually just annual mowing or burning, and some weed removal (mostly in the few years after installation)

This, like green roofs and green walls, is becoming a new market for both growers and landscape contractors. With Portland leading the way in this area, it will be one more topic this blog will continue to follow. If you are interested in more details, go to www.portlandonline.com/BES/, click on “Stormwater Solutions” under Library.

Watch for the upcoming post that discusses and provides references on the plant material being used in this newest version of sustainable horticulture.

Plant Lists for Green Roofs Continues to Expand

Posted by sustainable_hort on February 27, 2010  |  No Comments

Every green roof requires plants of some kind. While various succulents have proven relatively dependable in a roof’s harsh environment, there are many research projects looking at many other plants. As the results come in, new opportunities for the nursery industry and growers will appear.
But, at this point, there still seems to be a rather limited view of what plants might be best on our roofs. This post is part one of a two part article on green roof plants and environments. The second section will look at the basic types of green roofs we now see being built. This post also contains an extensive reference list.

Plants for Roofs
When reviewing plant use on green roofs, it is useful to first divide the discussion into “extensive” or “intensive” use.
“Extensive” roofs are generally installed for environmental/ecological reasons, not as additional human living space. If the roof is visible from surrounding buildings, the plant material may be irrigated, but often it is not watered. So, only tougher varieties that can go dormant for dry periods are chosen.
Define “intensive”…Moves beyond the purely environmental uses to creating livable spaces…multi-use spaces defined and enclosed in almost traditional landscape plantings though many of the plants are at a smaller scale. Use of containers, raised beds, and deeper soils allow for larger and vertical varieties. This concept is more developed in
Europe, though the re-urbanization movement with more concentrated condo living may demand more of these spaces be developed.
Yet, even within the more limited “extensive” options, the plant palette is still a work in progress. As Nigel Dunnett and Noel Kingsbury wrote:
“The horticultural potential of green roofs has yet to be fully realized. The majority of extensive green roof rely on a small number of species and cultivars that are use ubiquitously.”…”Widening the range of plant species used beyond the widely used sedum carpets has many potential benefits.” (b)

Broadening the Research on Plants for Green Roofs

Part of what Snodgrass called being “discovered” was all the research on the plants and soils for these roofs that has exploded in the last several years. After some notable green roof failures (see below), specific plant research is acutely needed so regional collections can be developed that will be successful in most situations.

Soil Depth Key to Plant Variety Success
Soils are one area of active research. The proceedings of the Green Roofs for Healthy Cities annual conference contain many reports and papers on soil make-up and depths relating to successful plant establishment on green roofs.
Add decades of practical experience, especially in Europe, and there are some basic parameters on soil depth and successful plants. The shallowest soils, with only 2 – 3 cm (0.8 – 1.2 inches) of medium, will grow only sedums and mosses. Substrate depths of 5 – 8 cm (2 –3.2 inches) support a wider range of succulent species, grasses, and herbaceous plants. Depths of 10 – 20 cm (4 – 8 inches) allows for a wide range of drought-tolerant perennials and grasses to be grown, as well as tough sub-shrubs. These depths will also support turf grass and lawns. Depths of 30 – 50 cm (12 – 20 inches) will support many perennials and shrubs to be grown. Trees generally need depths of 80 – 130 cm (32 – 52 inches).
The soil media composition is just as important as media depth to plant variety success. The percentage of organic to mineral matter, and the organic source material’s nutrient providing capacity, both play roles in the plants’ success. There are many ongoing research projects that will help determine which of the various media mixes work best in specific climates and situations. Soils need regional versions, similar to the choices with plants.

The Regional Need…
It is also generally accepted that one plant, or even one plant family, will not fit all the varied roof environments, due to both climate and differences in roof height and configuration. As mentioned above, nurseries like [Snodgrass] recognized the trend early, began with plants already successful in the regional climate, and began supplying contractors.
Nigel Dunnett discussed the same issue, stating…”because roof greening originated in central and northern Europe, the limestone meadow flora of this region has tended to dominate the plant-selection…partly because of its eminent suitability and partly because a variety of seed mixes are readily available. Yet, outside this region this limestone meadow flora may be regarded as inappropriate or potentially unsuccessful, particularly in areas with longer and hotter summers, making it important that local mixtures are investigated for their suitability instead.” (e)
The Northwest climate is a perfect example of a region that is probably not well understood. It has an image of grey skies and rain, yet is has a Mediterranean climate with little summer rain. This is different than much of the US that can have significant summer rains.

Early Northwest Project Teaches Hard Lessons
In fact, an early eco-roof in Portland provided a lesson in what not to do. The project, a green roof on the new Brewery Blocks development in northwest Portland was designed by Gerding Edlen Development. They eventually faced challenges at three points: drainage, soil and plants selection.
First, they misjudged the need for some slope in the drainage pattern. Since run-off was to be slow, they felt the level roof should not prevent water from eventually moving off. But, the roof was not completely level, and their drainage boards were too thin, leading to a pooling of water. Many of the plants did not like their “feet” wet and died.
Then, the soil had too much organic material. Most successful green roof soils have a small percentage (no more than 10%) organic material and are mostly made of inert materials such a perlite, ground lava rock, and other light-weight materials. In fact, many of the successful genera and species thrive in low-nutrient, sandy conditions, as mentioned above.
Finally, there was the plant selection. When designed in 2002, there was limited information on green roof plants. GED looked to Europe, borrowed many of the German succulents. But, they did not survive Oregon’s wet winters and very dry summers.
These problems were solved several years into the project by just starting over. Lessons learned, more information available, and hiring several experience consultants helped turn it around.
GED partner Dennis Wilde summed up the experience:
“First, hire landscape architects that have vegetated roof experience,” he stated in a 2008 Eco-Structure magazine article. “(Then), develop a deep understanding of the drainage, soil and plant issues you need for a successful installation.” (r)
At this point, most regional research continues to concentrate on plants that evolved in exposed soils, often mountainous areas, with rocky, sandy or xeric conditions. Adapted to cope with a lack of water, the plants have a morphology (see below) that stores water and reduces water loss. Many have fleshy leaves and stems that help deal with drought and high temperatures, with Sedums being the dominant choice. (n)
Dunnett presented research that showed there runoff was not generally affected by vegetation complexity or taxonomic composition of the communities. He noted seasonal differences. The winter months’ high precipitation quickly saturated the soil run-off was similar from all treatments. In the summer, with intermittent rains, run-off differed in relation to the plant canopy structure, where precipitation is lost to interception, stem flow and evaporation, along with transpiration.” The thicker the vegetative cover during low rain periods (summer), the more effective the roof is at capturing rain.(z)

Heavy Use of Sedums (Succulents)
As mentioned above, the heavy use of sedums is based on their survival rate in generally harsh environments. These plants will both store water and have a special type of metabolism called ‘Crassulacean Acid Metabolism’, CAM for short. CAM plants are unique in that under drought conditions their stomata (leaf pores) are open at night rather then during the day, as is the case with most plants. CAM plants exchange gasses (oxygen and carbon dioxide) in the dark when it is cooler and less windy. CAM plants are up to ten times more efficient with water conservation than non-CAM plants.
Many of these same plants will also go dormant, particularly during the drier periods. This is particularly important in the west coast’s Mediterranean climate. While some regions actually have a “wet” reputation, these states can be relatively dry from late spring until mid-Fall. This is in direct contrast to much of the US where summer rains are common.
This gives them a decided advantage when green roof conditions dictate certain limitations. Thus, the majority of green roofs you visit will have at least some sedums and succulents. Some roofs will be nothing but these plants.

Research Confirms Sedum’s Strengths
2006 research from Michigan State University tested sedum’s repudiated superior performance in low water conditions, common on green roofs. 25 Sedums were compared to several Michigan natives. The plants were watered at varying intervals. The non-sedum natives only survived if they received water every two days. In contrast, several sedum varieties were alive after 89 with no water. (a).
These plants have been used in Europe for decades, so early U.S. designers borrowed the palette without necessarily having the same climate. Results have been less than perfect. This may be due to the fact that much of Germany receives significant rain amounts in the summer and different winter conditions than many U.S. regions.

Nurseries Find Success with Succulents
Emory Knoll Farms, now possibly the largest U.S. green roof plant nursery, currently grow more than 100 different varieties for green roofs. Snodgrass’ choices are based on European sedums, selections from the Denver Botanical Garden, and many plants from South Africa, particularly the Ice Plant varieties. (d)
Green Living Technologies lists nearly 50 Sedum cultivars that are used in their hybrid mat-layered systems (see more below).
Intrinsic Perennial Garden is another supplier of green roof plants, They even have their own blend of native plants called the BIO-diver-CITY™ Blend These are Midwest native plants selected by Intrinsic Perennial Gardens, Inc. after trialing over 100 plants for the tough conditions of a green roof environment in the Midwest. (x)

Grasses
Green roof varieties drop off quickly after the sedums and related plants. A more limited range of grasses have also been successful, including many Festuca and Carex choices/
Grasses usefulness in green roof planting depends significantly on soil depth. Research indicates that very shallow soils (5 cm and less) will only support a couple small Festuca species and a restricted range of short sedges (b). Thus, the Festuca species appear on many green roof plant lists.
Yet, grasses continue to be popular choice since many can go dormant and revive vigorously when watered, or the rains return. Yet, several authors have noted a concern that they might create a fire hazard. This may represent another area of research.
Still, other varieties are suggested for use on green roofs. These include the following grasses and grass-like plants.
• Agrostis pallens (Bent grass)
• Calamagrostis stricta (Slimstem reedgrass)
• Panicum virgatum (Switch grass)

Other Choices
Meanwhile, the more aggressive nurseries are now offering the following plants: ferns, Alliums, many herbaceous perennials, and even mosses. The research below contains many newer choices now being tested.
It was surprising that research showed mosses might play a more important role in establishing a green roof than has been recognized. A recent paper discusses the BRYOTECH Process, a method developed for the industrial production of pioneering plant mosses associated with microorganisms. The authors provide brief summaries of results of studies that explored the effects of soils with a “biological crust” on plant growth and performance. According to the authors, mosses and other symbiotic plants and soil micro-organisms can create green roofs that immediately incorporate the living elements that nature would introduce over a much longer period of time: micro-organisms associated with mosses, and wild seeds of dependent xerophilous plants. The need for maintenance of plants and the use of fertilizers is greatly reduced. The various studies and works carried out by the firm MCK Environment demonstrate that the use of mosses is key in re-vegetating land where colonization is particularly difficult. This principle is also applicable to green roofs. (t)

References:
Those interested in plants for green roof should get a subscription to “Eco-Structure” magazine (www.eco-structure.com); and “Living Architecture Monitor,” published by Green Roof for Healthy Cities, (www.greenroofs.org).

(a) Evaluation of Crassulaceae Species on Extensive Green Roofs. Durhman|VanWoert|Row|Rugh|Ebert-May, Angela K. |Nicholaus|D. Bradley|Clayton L.|Diane. Proceedings: Greening Rooftops for Sustainable Communities 2004, 2004, 3.6.

(b) Plant Options for Extensive and Semi-Extensive Green Roofs. Nigel Dunnett and Noel Kingsbury. Proceedings: Greening Rooftops for Sustainable Communities. 2004 conference proceedings, 2.2.

(c) Native Coastal Plants for Northeastern Extensive and Semi-Intensive Green Roof Trays: Substrates, Fabrics and Plant Selection: Jeff Licht, EdD, LLC, Jeremy Lundholm, PhD Wayland, MA, Roof Garden Consultant / St. Mary’s University, Halifax, Nova Scotia, Canada Rooftops for Sustainable Communities 2006, conference proceedings, 4.3.

(d) Green Roof Plants. A Resource and Planting Guide. Edmund C. and Lucie L. Snodgrass. Timber Press. 2006

(e) Planting Green Roofs and Living Walls. Nigel Dunnett and Noel Kingsbury. Timber Press. 2004.

(f) Rain Gardens. Nigel Dunnett and Andy Clayden. Timber Press. 2007.

(g) Plant Options for Extensive and Semi-Extensive Green Roofs. Nigel Dunnett and Noel Kingsbury. Proceedings: Green Rooftops for Sustainable Communities 2004 conference proceedings, p 16.

(h) Water-Efficient Plants for the Willamette Valley. Regional Water Providers Consortium publication. Information at www.conserveh2o.org.

(i) The Green Fuse: Using Plants to Provide Ecosystem Services. Sustainable Plant Research and Outreach (SPRout) publication. A literature review. Rene Kane. 2004

(j) Evaluation of Sedum ternatum in a Shaded Green Roof System. C. Hise, V. Jost, K. Luckett, S. Morgan, T.Yan, and W. Retzlaff. Southern Illinois University Edwardsville, 2006.

(k) Plant Species Evaluation for Extensive Green Roof Applications in the Midwestern United States. S. Kaufman1, V. Jost2, K. Luckett3, S. Morgan1, T. Yan1 and W. Retzlaff1. 1Southern Illinois University Edwardsville. 2006.

(l) Evaluating Plants in Green Roof Systems Following Establishment. Sydow M.1, K. Forrester2, V. Jost3, K. Luckett4, S. Morgan5, and W. Retzlaff1, 2. 1Department of Biological Sciences; 2Environmental Sciences Program; 3Jost Greenhouses; 4Green Roof Blocks, St. Louis MetalWorks, Inc.; 5Department of Civil Engineering; Southern Illinois University Edwardsville. 2006.

(m) Evaluating Green Paks Green Roof Systems. R. Lucas1, H. Luckie1, V. Jost2, K. Luckett3, S. Morgan1, T. Yan1 and W. Retzlaff1. 1Southern Illinois University Edwardsville, Ill. 2006.

(n) Native Survivors. By Ron M. Wik, Living Architecture Monitor, pages 24 – 25. Winter 2008.

(o) Hot and Humid, What Plans Work Best in Tropical and Subtropical Situations? By Steve Skinner, Living Architecture Monitor, pages 26 –27. Winter 2008.

(p) Drought…Evaluating the Performance of Green Roof Plants and Growing Medium. By Dr. Bill Retzlaff, Dr. Susan Morgan, Kelly Luckett and Vic Jost. Living Architecture Monitor, page 29. Winter 2008.

(q) Oregon State University Stater, Winter 2008, pages 21 – 26.

(r) Best Intentions, article by Jim Schneider, Eco-Structure magazine, April 2008, p. 44 – 47.

(s) Establishment and persistence of Sedum spp. and Native Taxa for Green Roof Applications, By Monterusso, Michael A., Rowe, D. Bradley, Rugh, Clayton L., Michigan State University. HortScience 40(2):391-396, April 2005.

(t) Mosses, A Necessary Step for Perennial Plant Dynamics. Chiaffredo|Denayer, Michel|Franck-Olivier.. Greening Rooftops for Sustainable Communities, Portland, OR, June 2-4, 2004, p. 9.

(u) 100 Extensive Green Roofs: Lessons Learned. Snodgrass, Ed. Proceedings: Greening Rooftops for Sustainable Communities, May 4-6, 2005, p. 6.

(v) White|Snodgrass, John W.|Edmund. Extensive Greenroof Plant Selection and Characteristics. Greening Rooftops for Sustainable Communities, p. 14.

(w) Whitlow|Compton, Thomas|Jeannette S.. 11-MAY-2006. A Zero Discharge Green Roof System and Species Selection to Optimize Evapotranspiration and Water Retention. Greening Rooftops for Sustainable Communities, Boston, MA, May 11-12, 2006, p. 12.

(x) Hauth|Liptan, Emily|Tom. 30-MAY-2003. Plant Survival Findings in the Pacific Northwest. Greening Rooftops for Sustainable Communities, Chicago, Illinois, May 30, 2003, p. 13.

(y) Rowe|Monterusso|Rugh, Bradley|Michael|Clayton. 01-JAN-2007. Evaluation of Sedum Species and Michigan Native Taxa for Green Roof Applications. Greening Rooftops for Sustainable Communities, Washington, DC , May 2-4, 2005, p. 13.

(z) Dunnett|Nagase|Booth|Grime, Nigel|Ayako|Rosemary|Philip. Vegetation Composition and Structure Significantly Influence Green Roof Performance. Greening Rooftops for Sustainable Communities Greening Rooftops for Sustainable Communities, Washington, DC, May 4-6, 2005, p. 10.

(aa) Taken from Blackdown Horticultural Consultants Limited’s PDF brochure, available at www.greenroof.co.uk.

(bb) Article “Just Add Water: Wetlands Green Roofs for Enhance Performance” in The Green Roof Infrastructure Monitor, Fall 2007, p. 6 – 9.

(cc) Houghten, F. C. et al. 1940. Summer cooling load as affected by heat gain through dry, sprinkled and water covered roofs. ASHVE Transactions. 46:231-242.

References for New Plant Technologies

Posted by sustainable_hort on February 10, 2010  |  No Comments

This is in response to a comment on this blog’s post on new environmental uses of plants. The visitor had hoped for more specific information on the plants that the “new plant technology” required. When I speak on this topic, I include references that include commonly used plants. So, this is a quick list to help you identify the types of plants used for these new technologies.
Since I work directly with a green roof technology and system manufacturer, I have had exposure to the plants this unique environment requires. Two books will give most readers, and even growers, more than enough to get started. First, is Planting Green Roofs & Living Walls by Nigel Dunnet and Noel Kingsbury. In its second edition, this is a solid basic discussion of green roofs and walls, and contains a useful plant list.
Growers will find Ed Snodgrass’s Green Roof Plants a perfect place to start. Ed runs the most successful green roof plant nursery in the US, and has done much of the heavy lifting to summarize what we know works in green roofs, mainly the extensive or eco-roof models. Once the design moves into an “intensive” stage, it is treated much like any landscape, though the supporting technology is different.
Since an alternative technology for green walls involves wire frameworks covered in fast growing vines and climbing plants. Good resources include the Manual of Climbers and Wall Plants edited by J. K. Burras; and Vines and Climbers: A Gardener’s Guide to the Best Vertical Plants by Allan M. Armitage. All the above books are available through Timber Press at www.timberpress.com.

Green landscaping, restoration work and other ecological projects often focus on using natives, a whole different group of plants with regional differences. One useful publication is Rain Gardens: Managing Water Sustainably in the Garden and Designed Landscape (Timber Press) by Nigel Dunnett and Andy Clayden. Another related text is Wetland Ecosystems (John Wiley & Sons, Inc.) by Mitsch, W.J., J.G. Gosselink, C.J. Anderson, and L. Zhang. (2009) A more general text on using natives is Selecting Native Plant Material for Restoration Projects, written by By B. Winthrow-Robinson and R. Johnson . It has additional references and can found at http://extension.oregonstate.edu/catalog/pdf/em/em8885-e.pdf. I would suggest contacting your state Extension Service for regional lists of restoration and native plant material.
As I come across other related publications, I will post them on the site. Thanks for the question.

A Landscaper Looks at Sustainability

Posted by sustainable_hort on February 4, 2010  |  No Comments

In my recent post , New Opportunities in Sustainable Landscapes, the discussion centered on new landscape directions for the industry. This post looks at how one landscape firm looks at creating a different landscape, one focused on sounder environmental principles.

“Sustainability does mean change and that’s the reason we are hearing about it all the time,” said David Sandrock, owner of Sustainable Landscapes for the Pacific Northwest, Corvallis, Oregon.
“But, it is an opportunity,” he said during his presentation at last November’s OLCA Expo. “People are looking to us for solutions.”
Sandrock said that “sustainability” is based on several key concepts.
The former Oregon State University professor said the first concept is often used as a definition of sustainability.
“Sustainable action is development that meets the needs of the present without compromising the ability of future generations to meet their needs,” he offered.
This, in turn, takes intelligent resource planning, he said, and added that this movement emerged in response to human misbehavior.
“These actions move toward landscapes that we can depend on, not landscapes that depend on us,” he concluded. “It will require a return to the art and science of horticulture.”

New Opportunities in Sustainable Landscapes

Posted by sustainable_hort on January 30, 2010  |  1 Comment

This article appeared in the Oregon Landscape Contractor’s magazine. It is related to my last post that discussed how growers, retailers and landscapers might take advantage of new “green” trends and technologies. This focuses on how “Sustainable Development Offers New Opportunities for Landscape Contractors.”
And…thanks for your many positive comments on my content. Much more to come.

Many major developers are ‘going green,’ not just for good public relations, but also as an economically beneficial strategy. Innovative landscape firms have a tremendous opportunity to join this effort, position themselves as “green,” and dramatically increase their business.
“These are not little changes, but this is a sea change,” explained landscape architect Paul Morris, speaking at the annual meeting of Oregon Landscape Contractor Association in December. By 2010, industry studies predict a $19 to 38 billion in the residential green building market, he said.
Morris works on planning and sustainable issues for Cherokee Investment Services, Inc., an international development firm. He said that his company has long recognized the many benefits of incorporating sustainable technologies into their projects.
“These are no longer just warm-fuzzy things we’d like to do,” said Morris. “There are calculable benefit costs that can now be identified.”
In fact, his company, with $2 billion in assets, is the leading private investment firm in “brown field” development, working on abandoned and idle industrial and commercial urban sites often with environmental degradation and contamination, distinguished from “green fields,” undeveloped land outside urban areas. It plans to spend $250,000,000 on remediation projects, he said.

Going Green – Point Tipped

Posted by sustainable_hort on January 29, 2010  |  4 Comments

This is an article I wrote several years ago, but with a few minor changes, it still applies to the nursery and landscape industries…maybe even more with the downturn in sales. The green industry needs to market its “greenness!”

Point Tipped…Going Green
By Miles McCoy

Even that wild-eyed, business-entertainer Jim Cramer has gone green.
It was a big turning point for the popular investment show host. He had long discouraged any investment in “green” companies because they did not have a sound financial underpinning.
That changed with recent Supreme Court decision…a true tipping point. (more on that later) The Supreme Court’s decision essentially changed the pollution playing field by declaring that carbon dioxide is a “pollutant.” It thus falls under the Clean Air Act and can be regulated by both the EPA and states. A Business Week’s article stated, “The door is now open for new lawsuits against companies that emit carbon dioxide.”
Strong stuff, but seemingly not unanticipated within the US or world business communities.
In fact, a former chief economist at the World Bank, Sir Nicholas Stern, recently wrote in a Business Week column (4/16/07 – p. 90), “reducing carbon emissions is a pro-growth strategy, not an economic burden.” There is more evidence as companies as diverse as Goldman Sacs and Wal-Mart have announced major “green” efforts within their structure.
This change continues to be driven more by consumers and popular media. Vanity Fair just presented it second annual “green” issue, while a recent Newsweek cover features California’s green governor Arnold Schwarzenegger. A week earlier, the magazine’s “Tip Sheet” gave readers advice on creating a “greener garden,” with facts on native plants (another topic!), saving water, composting, mulching, and organic pest/weed control. A recent New York Times article on organic lawn care asked “are bugs the pests, or humans?!” Consumers are speaking at the cash register, demanding safe, natural products to care for their landscapes. More on that in a minute.
Meanwhile, green buildings are all the rage, with the Leadership in Energy and Environmental Design (LEED) certification now crucial, and even mandated, for new construction. While much of the green technology has little to do with our industry, we are seeing a greening of our roofs. These roofs are sold as offering environmental solutions. They may only develop a minor, niche for growers, but their concept of marketing may give the overall green industry some viable advertising themes.
For instance, should we encourage homeowners to include landscapes that handle the run-off from their home and driveways? Green roof activity is often driven by storm-water runoff control, using the roof’s plants and soil to hold back large rain events. Portland has gained a national reputation for creating what an Oregonian editorial recently described as our “greener, gentler streets,” where run-off swales are actually built into the streets. So, maybe the industry can promote ponds and swales with their water-loving plants; or pervious driveways that use tough, low-growing plant choices. New environmental options will often require our plants.