When you meet landscape architect Thomas Rainer he comes across as a pleasant, mild mannered fellow… not at all the type to be traveling around the world, as he does, spouting revolutionary ideas calculated to upend years and years of conventional gardening wisdom. As he writes in his preface to Planting in a Post-Wild World, the 2015 book he wrote with Claudia West, his ideas come from his time as a boy in suburban Birmingham, Alabama where he spent countless happy hours roaming a stretch of indigenous Piedmont forest near his home. His playground was lost to development when he was in high school. As an adult, he still mourns its loss. But he is also a realist who understands that the worldwide development juggernaut is not to be stopped and that the original spaces which are lost can never truly be put back as they were.
Instead, in his work as a landscape designer, educator, author—and now partner in the new landscape design firm Phyto Studio—Rainer has developed a horticulture philosophy that advocates transforming the green spaces that remain (including such unpromising remnants as hell strips, the edges of parking lots and the tops of buildings) into vigorous, low-maintenance landscapes that mirror the way plants grow together naturally. As a result, Rainer boldly asks us to use methods that fly in the face of how gardeners have worked the land for generations.
Read on for his dos and don’ts for growing an earth-friendly garden that he says produces better results with less work.
Photography courtesy of Phyto Studio.
1. Amending the Soil: Don’t
Above: Photograph by Thomas Rainer.
Conventional site preparation encourages amending the existing soil until it resembles a kind of generic potting mixture: loose, friable, deeply fertile black dirt. However, Rainer says, “Plants don’t want generic soil, they want specific soil.” Far better, he says, to choose plants that will thrive in the soil you have, rather than trying to create an artificial environment for plants that wouldn’t naturally grow where you want to plant them.
2. Double Digging: Don’t
Above: Photograph by Claudia West.
When I started gardening in the early 1990s, books I consulted advised preparing planting beds using a back-breaking method called double digging—whereby layers of soil were removed from the bed, mixed with plenty of amendments and replaced. When I asked Rainer if double digging is obsolete, he assured me that it certainly is unless you have a site with severely compacted soil. He says double digging and other methods of site preparation such as tilling destroy the natural soil layers, disturb helpful mycorrhizae (the mutually beneficial underground relationships that form between plant roots and fungi), and create perfect conditions for weeds and invasive species.
3. Soil Testing: Do
Above: Photograph by Claudia West.
Rainer is not totally opposed to giving some help to young plants. He advises having your soil tested by a reputable lab so that you can make informed choices of plants that will adapt well to your garden. He says if you have 4 to 5% organic matter, there is no need for amendments. Some modest additions to the soil when young plants are installed, such as compost tea and a light compost top dressing, are usually all that is needed to give seedlings the boost they need to adapt to their new environment.
4. Mulching: Don’t
Above: Photograph by Claudia West.
Ditch the mulch, and use plants instead. Rainer bemoans the American love affair with mulch and says it is far better to cover bare garden soil with plants. Perennial ground covers will discourage weeds better than mulch and, once established, will require far less work than mulch, which breaks down and must be replenished or replaced. Underplanting structural shrubs such as roses and azaleas with softer-looking ground covers such as sedges, wild ginger, or coral bells provides an attractive contrast between the two very different types of plants and looks more natural than a lone shrub surrounded by swaths of wood chips or ground-up bark.
5. Planting Cover Crops: Do
Above: Photograph by Claudia West.
Cover crops are not just for farmers. Rather than feeding your garden with compost or other material, use cover crops on bare soil. On empty spots where perennials have died back or annuals have run out of steam in the fall, plant a shallow-rooted crop such as the fracking forage radish (Raphanus sativus), which can be planted in August or September for green coverage all winter. In the spring, when it dies, its stems and leaves as well as its roots will break down, adding nutrients without any disturbance to the soil. In addition the decaying roots will help to aerate the soil and prevent compaction.
6. Curbside Planting: Do
Above: Photograph by Thomas Rainer.
When laying out a garden, let nature be your guide—and don’t leave plants isolated with lots of bare or mulch-covered space around them. For far too long, he says, we have treated plants as individual artifacts arbitrarily placed in designs that largely ignore their needs. It is much better, he says, to study plants in the wild and use them in our gardens the way they would appear in nature, as part of a plant community with common cultural needs. In natural settings plants tend to form interdependent groups where each type of plant works with the others to make the most of limited sunlight, water and nutrients.
7. Buying A Lot of Plants: Do
Above: Photograph by Claudia West.
Don’t hold back; plant generously. To get a new garden fully planted, you will initially need many plants. Rainer advises investing in a few key large specimens and buying everything else as small as possible.
When you buy a large perennial from a nursery, you are paying a lot for a plant that was nurtured in a perfect environment. But, Rainer points out, your garden will not offer the same climate-controlled greenhouse conditions. Better to start with smaller, younger specimens that will adapt to a new environment faster. To get full coverage, use plugs (small-size seedlings) and plant a lot of them. The less disturbance the better when installing plants so one of Rainer’s recommended methods is to drill narrow holes in the soil with an auger and then drop in the tiny plants.
8. Experimenting and Having Fun: Do
Above: Photograph by Thomas Rainer.
Rainer’s final tip is one that is often forgotten amid the chores of gardening. “Have fun,” he says. “Gardens are not meant to endure but to enchant. The life is what is important. Gardening should be a joy.”
N.B.: See more of our favorite ideas for planet-friendly gardens: