Sustainability in the Garden

By: Dean DeSantis

Dean DeSantis, president of DeSantis Landscapes (www.desantislandscapes.com), is the second-generation owner of this landscape design/build/maintenance business, which was founded in…

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Compost tea and organic fertilizers keep this landscape thriving. Author’s photographs, except as noted

Compost tea and organic fertilizers keep this landscape thriving. Author’s photographs, except as noted

In 1987, a United Nations Commission, the Brundtland Commission (named after its chair Gro Harlem Brundtland), argued that sustainable development is “development that meets the needs of the present without compromising the ability of future generations to meet their own needs.” As Dr Brundtland put it, “the environment is where we all live, and development is what we all do in attempting to improve our lot within that abode. The two are inseparable.”

As people interested in horticulture, whether we are “developing” our own small plot of land at home or a larger commercial property, we must consider the inseparableness of our development actions and the environment. Most, by now, have heard of LEED (Leadership in Energy and Environmental Design) certification, a third-party, green building rating system administered by the US Green Building Council. This program focuses primarily on the building envelope (walls, roof, etc), building systems, and construction technologies. New to most is the Sustainable Sites Initiative, a similar third-party certification program; still in the development stage, it is not planned to officially roll out until 2012. The guiding principle of this initiative is to “preserve or restore a site’s sustainability within the context of ecosystem services,” those natural assets that provide a full suite of benefits and services to humans and other organisms.

A Portland garden that has been regularly treated with compost tea, but no chemicals

A Portland garden that has been regularly treated with compost tea, but no chemicals

Healthy Soils

Clearly there are real and tangible benefits to healthy soils, healthy plants, and good water management. These are some of the areas that we touch in our daily work as horticulturists and plants people. Healthy soils are where it all begins. As a landscape contractor, I’m concerned that our industry does not do enough soil testing. As observant professionals, we generally know an area’s soil type, but a lab test can provide valuable information about the idiosyncratic needs of a particular patch of ground. Our goal is to provide nutrients and to activate microbial life in the soil to feed the plants we are hoping to grow. To this end, we have had success with compost teas and a balanced fertilization program. We brew and apply our own tea and can customize the brew according to the needs of a particular site.

The photographs show a garden on which we have applied tea for the past four years, along with natural, slow release fertilizers. There have been virtually no pesticides used here during that time. Soil tests confirm a much healthier and biologically active soil than when we began the transition from a conventional fertilization program. We spray the tea directly onto the turf and planting beds, and use a foliar spray on the plants. Three to four applications per year have proven to be effective. Chemical-based pesticides and some synthetic fertilizers can kill a range of beneficial organisms that would improve plant life. In contrast, compost tea adds to and promotes what soil specialists sometimes call the “micro-herd” of beneficial organisms. If you are not a soil scientist, the website for Soil Food Web (www.soil foodweb.com) is a helpful and educational resource on all matters related to compost teas. The tea adds the biology and our fertilizers add the nutrients to feed not only the plants but the biological micro-herd. We’ve found that employing one without the other is far less effective.

Proof that a pesticide-free garden doesn’t have to look like a weed patch

Proof that a pesticide-free garden doesn’t have to look like a weed patch

Mulch Matters

In landscapes on the West Coast, it is common to use fir or hemlock bark mulch to top-dress planting beds. While bark mulch serves to retain moisture by shading the soil, thereby reducing weed seed germination, it adds little to the soil biology; in fact, natural toxins in the bark can actually have a negative impact on the soils. Good gardeners have long understood the benefits of using garden compost as topdressing. Good compost offers the beneficial organisms that help with moisture retention and weed control and provides us added nutrient value. Think of it as feeding the soil micro-herd that in turn sustains your plants. Finding quality compost in bulk, however, can be a challenge. Compost facilities rely on contractors and others to supply them with yard waste that they process into a usable product. Controlling what comes into their composting facilities is difficult; as a result, we often see in purchased compost a lot of plastic that has come from chopped up bits of irrigation tubing, plastic pots, plastic sheeting (for weed control), and yard waste bagged in black plastic by both homeowners and landscape professionals. Plastic typically will not decompose, although there are now some lightweight compostable plastic bags. If your yard waste must be bagged, use paper. Vigilance and feedback to compost suppliers will help ensure a consistent caliber of compost.

A rain garden at the Estacada Library uses recycled materials and wetland tolerant plantings to transform the foundation landscape into a functional and aesthetic feature. Water from the building downspout is conveyed away from the building to an artistic circular depression where it can pond temporarily as it slowly percolates into the soil. Photograph courtesy of GreenWorks, PC

A rain garden at the Estacada Library uses recycled materials and wetland tolerant plantings to transform the foundation landscape into a functional and aesthetic feature. Water from the building downspout is conveyed away from the building to an artistic circular depression where it can pond temporarily as it slowly percolates into the soil. Photograph courtesy of GreenWorks, PC

Water Issues

Water supply and water quality are two areas that demand our focus and innovation if we are to meet the needs of future generations while serving our own. By many estimates, up to fifty percent of summer water use is for landscapes, and half of that is either wasted or unnecessary due to overwatering, overspray, poorly adjusted irrigation heads, or leaks in the system. There is a huge potential for water savings through improvements in irrigation systems. We now have rain sensors, wireless remote controls, central controllers, flow controls, two-wire technology, weather stations, and more. The greatest technologies in the world are rendered moot, however, without a skilled operator. If you are going to depend upon anything other than hand watering, I recommend getting educated or getting qualified help.

Stormwater Management

We are just beginning to acknowledge the advantages of stormwater management. Take a look at any waterway during a storm event, and you can find any number of pipes dumping the stormwater coming off of our streets, our parking lots, and our buildings. Planners and developers typically use the “hundred-year rain event” data for designing and engineering surface water movement through a site. We now find that those rain events are being reached more and more frequently. As development goes, so goes piping into our waterways.

Smart developers, however, are finding alternatives. Through the use of rain gardens, bioswales, and phytotechnology, we have the ability to handle the majority of any storm event right on site, to cleanse the pollutants from the storm runoff, and to slow the flow into our waterways, thus minimizing the sharp spike in water levels. Phytotechnology is the science of putting plants to work to provide ecosystem services. Absorbing storm-water and cleansing pollutants is an important ecosystem service. The City of Portland has a downspout disconnect program that pays homeowners to disconnect their downspouts from the city sewer system. Directing the flow into a rain garden, where plants and soil can absorb the stormwater, is a practical and attractive proactive solution that avoids turning a lawn or other area into a messy bog. We’ll need more of this type of incentive program to encourage and educate homeowners and developers to protect our waterways from the negative impacts of “conventional” development.

I have twins who will be nine by the time you read this. While they are just starting to be conscious of the larger world outside our family, their school, and the town, I have serious concerns for what our planet will be like when they’re my age. I want to do what I can do to ensure that we are meeting the needs of the current times without compromising the ability of our children’s generation, and their children’s generation to meet their needs. As horticulturists, landscape professionals, gardeners, and plant lovers, there are many opportunities for us to take the lead in creating a sustainable future. Pick one and do it.