Be A Better Gardener: Choose Plants for Your Soil

by Thomas Christopher

“It all starts with the soil,” Neil Diboll says to me.

I met Neil in 1990 while attending a prairie restorationists’ conference in Iowa. A year or two later, I visited the Prairie Nursery that he had created in Westfield, Wis. Neil had completed a degree in environmental sciences at the University of Wisconsin and later joined the university staff to assist in the restoration of a prairie at its Cofrin Arboretum. From there, he turned his hands-in-the-soil experience and ecological expertise to what was then an unheard-of enterprise: raising prairie plants for sale to the public. Hand in hand with this was an educational program to help customers learn how to combine such plants into naturally inspired gardens that could flourish with a minimum of maintenance while also reinforcing or reviving local ecosystems. Just how strange this was regarded at the time was evidenced by the locals’ nickname for Prairie Nursery: “the weed farm.”

During my first visit to his nursery, Neil told me with a grin, “All your gardens are in intensive care.” He was right, I came to understand. By ignoring the principles by which plants interact with each other and their environment, horticulturists such as me, whether we were working with traditional garden plants or, what was then a new concept, plants indigenous to our area, selected them purely on aesthetic grounds and treated them as individuals rather than as interrelated elements in a community.

As Neil emphasized in a conversation I had with him a few weeks ago, our first mistake was to adjust the soil on our site to suit the plants we had already selected. This is an approach that is still too common. Because a Kentucky bluegrass lawn is considered a necessity by the average homeowner, we pay a contractor to spread a couple of inches of loam (“topsoil”) over whatever kind of soil is found on the site. The grass roots stop growing when they reach the native soil, which gives them a scant reservoir from which to draw moisture and nutrients, so we must compensate with frequent watering and fertilization, and perhaps applications of lime if the soil is acidic. In the flower garden, we more commonly work harder at transforming whatever it is nature has given us, digging in copious amounts of compost or peat, fertilizers, and perhaps more lime to create beds of artificial fertility and good drainage. Nor is this a once-and-done process: every year we add more resources and energy to keep the soil from gradually reverting to its origin.

As Neil emphasized, there are communities of plants that will flourish even in the most extreme soils. He grows “clay busters” whose roots can penetrate the heaviest clay soils, opening channels and adding organic matter. He sells other plants that naturally inhabit soils so sandy that earthworms can’t tolerate them and ants take over the job of tunneling and pulling organic matter underground.

Finding a “community” of plants (species native or introduced that associate naturally) that are adapted to your soil provides a palette of species that will cooperate in colonizing your landscape. The first step to identifying such a community is determining the characteristics of the soil in your backyard. Neil still promotes gardener education, and the “Learning Center” on Prairie Nursery’s website (www.prairienursery.com) includes an entry, “Understanding Your Soil,” that details home tests that can help the gardener explore such characteristics as soil type and structure. 

The Prairie Nursery online catalog, which offers woodland as well as prairie plants, groups species by their soil adaptation, which is a useful starting point to identifying a community. Neil is also co-author with Hillary Cox of a very valuable book, The Gardener’s Guide to Prairie Plants which includes a compendium of species lists of plants adapted to different sorts of conditions. For a guide that is national in scope, Neil recommends the “Search for Plants” function on the Lady Bird Johnson Wildflower Center website (https://www.wildflower.org/plants/).

Identifying communities of introduced, non-native plants adapted to different soils is more challenging because there are fewer ecologists involved in that style of gardening. The Missouri Botanical Garden’s “Plant Finder” database is a good starting point for such a search.

To listen to the rest of my hour-long consultation with Neil Diboll about working with your soil, log on to the Berkshire Botanical Garden “Growing Greener” podcast at www.berkshirebotanical.org.

Be-a-Better-Gardener is a community service of Berkshire Botanical Garden, located in Stockbridge, Mass. Its mission, to provide knowledge of gardening and the environment through a diverse range of classes and programs, informs and inspires thousands of students and visitors each year. Thomas Christopher is a volunteer at Berkshire Botanical Garden and is the author or co-author of more than a dozen books, including Nature into Art and The Gardens of Wave Hill (Timber Press, 2019). He is the 2021 Garden Club of America's National Medalist for Literature, a distinction reserved to recognize those who have left a profound and lasting impact on issues that are most important to the GCA. Christopher’s companion broadcast to this column, Growing Greener, streams on WESUFM.org, Pacifica Radio and NPR and is available at berkshirebotanical.org/growinggreener.