As a landscaper, you have the opportunity to help your clients stay up-to-date with your skills and interest in making their property a welcoming habitat for birds, beneficial insects (think pollinators and beyond), and manageable wildlife. What’s another way you can do this? You may have already helped clients understand the importance of limiting fertilizers to areas where they won’t directly end up in a water source. You may have already helped clients understand the importance of designing with native plants, replacing some of the annuals and placing annuals in containers closer to a patio or entryway where they can be truly appreciated (and watered more easily.) What can be next on your list of ways to help your company stay in tuned to what is going on in the horticulture industry and the ecological landscape mind set?
Understanding phytoremediation may help in that communication with landscape architects or clients. Plants are used in successful ways, such as creating rain gardens, catching excessive runoff so the erosion is limited and roots in the planting area are absorbing contaminants from paved driveways, streets, or parking lots. Plants are used indoors as we have seen in the work done by NASA to research their purifying properties with indoor air quality. We think of plants such as spider plants or sansevieria as helping air quality in homes and offices – on a larger scale, trees are definitively shown to be able to help air quality and even reduce temperatures on city streets. These are all remediations on conditions caused by human activity where plants (phyto) are involved in improving the situation.
By using plants to absorb contaminants in the air, it doesn’t take much more thought as to how plants can absorb contaminants in soils. This is a technique used on large scale applications, such as brownfields sites, and is shown to be far less expensive than a crew with heavy equipment removing the contaminated soil and capping it at a hazardous waste location. In fact, it’s about 1/10th the cost! Once the plant growing cycle is complete, those workhorse plants are removed, burned, and only the remaining ash needs to be effectively and safely relocated as hazardous waste.
How does this translate to some homeowner properties? Knowing historical or previous uses of the location can offer clues to what might be compromising the soil there. Take a look at the Fact Sheet at www.epa.gov.phytoremediationresourceguide for learn more. In the phytoremediation guide, you will learn more about what this entails, what plants are recommended, and what realistic goals are with the phytoremediation techniques – as shown by long-standing research.
In New England, there are several noteworthy examples of phytoremediation techniques helping to greatly improve landscapes. The Loring Air Force Base in Maine, once it closed, became MicMac tribal property which they had hoped to use for farming. The soil was found to be contaminated with PFAS, and plants were called on for the rescue. The MicMac farming products in other locations included hemp plants, which are excellent candidates for the ways plants can absorb the PFAS contaminants. Hemp grows quickly, has deep, thick root structures, and can grow successfully in an array of light and water conditions. While one cycle of hemp plant growth and absorption of PFAS doesn’t remove all the contaminants, it’s a meaningful start. Since hemp grows quickly, a few cycles can be effective in this scaled situation.
That is a downside of phytoremediation – it’s not quick like a crew with heavy equipment moving the contaminated soil, and the phytoremediation only removes contaminants in the plants’ root zones. But, this is a reasonable beginning and has many realistic uses.
Back to homeowners’ sites and situations. Drip lines around garages or sheds with runoff from some roofing material may show compromised soils. Using plants to absorb those from the soil (ensure this area would not be used for vegetables or edibles) could be a way to improve the location for years to come. Various grasses can be used for these type of areas, to help to also detoxify places where pesticide use may have been prevalent or herbicides may have been used previously. Poplar trees, while not usually thought of as landscape design trees, should be given more thought. They grow quickly, and in addition to the ways their intensive root systems can absorb contaminants, they offer great habitat for many types of birds with their branching structure and early leaf out.
Check out the material available on phytoremediation from the Environmental Protection Agency (EPA.gov), and from sources available in the Ecological Landscape Alliance’s article archived by Kate Kennan, “Pollutant Purging Plants.” Plants in our yards and gardens offer beauty, habitat, and work in so many more ways to our advantage. Consider all these aspects of your designs and suggestions, as you include discussions about native plants and pollinators, include ideas about plants’ uses to improve soil, create sound barriers, and clean up the air all at once.
—by Cris Blackstone, NHCLP