“Loosening the grip on our cherished notions of plant arrangement makes it possible to transform our adversarial relationship with nature into a collaborative one.”
— Thomas Rainer and Claudia West, “Planting in a Post-Wild World,” 2015
I recently spoke with Ashland landscape designer Sherri Morgan, who heard Thomas Rainer speak last year at the International Master Gardener Conference in Portland.
“I was particularly intrigued by what he had to say about designing resilient landscapes,” Sherri said. “I think we’d all like our gardens to be more resilient and less work for us to manage.”
As we’re considering ornamental plantings for next spring, it’s a good time to think about designing what Rainer and co-author Claudia West call “plant communities.” These are groupings of native and non-native trees, shrubs, flowers and ground covers that share the same cultural requirements and are adapted to thrive under the site conditions we have. Plant communities support each other and local wildlife without as much intervention from gardeners, which is certainly a winning situation in my book.
According to Rainer and West, designing plant communities involves attention to five principles, the first of which is “letting go of the idea of plants as objects to be placed, like pieces of furniture.” Instead, group compatible species that interact effectively with each other and the landscape. Once gardeners understand their soil, sunlight, moisture and other site conditions, efforts can go toward selecting groups of plants that will grow well in that environment, rather than trying to change the conditions in order to grow plants that aren’t well suited.
The second principle has to do with plant stress. Instead of eliminating stressors, Rainer and West noted, plant communities are often healthier when they must adjust to limited resources. “Most gardeners water too much,” Sherri said. Over-watering makes plants more vulnerable to dry periods.
Principle three also challenges conventional wisdom by calling for less mulching with materials brought in from elsewhere, and more of what Rainer and West call “green mulch” — low-growing, shade-tolerant plants that fill up open spaces and provide natural weed control.
Ground covers occupy their own niche under a layer of mid-height plantings that become visually dominant in the plant community. This seasonally themed layer of plants establishes a niche beneath a structural layer of trees, shrubs and tall perennials.
Principle four takes into consideration cultural notions of landscape beauty. Rainer and West wrote, “Our cultural bias for tidy landscapes often limits the potential for ecological planting.” However, naturalistic plant communities aren’t wild. According to the authors, “They need not replicate nature in order to capture its spirit.”
Perhaps the fifth principle deviates the most from traditional practices. Instead of viewing and treating the plants in our garden and landscapes as individuals, we develop a more holistic perception of the plant community as a “complex, adaptive system.” Rainer and West noted that plant communities are managed, not maintained, and “watering, mulching, spraying, pruning and leaf litter removal are generally avoided.” Instead, garden management aims at preserving the plant community as a whole through tasks such as selectively removing or adding plants in order to preserve the community structure and balance of plant species.
I asked Morgan to share other suggestions for designing plant communities, and she said, “Become aware of the remnants of native plant communities that survive in your neighborhood.”
For example, Morgan’s home in Ashland is in the remnants of native forestland; my neighborhood in east Medford has remnants of the oak trees and grasslands that once flourished here.
Become familiar with plants that will grow naturally in the environment of your landscape. Planting natives is a good starting point, but compatible non-natives can also be used effectively.
“Native Pollinator Plants for Southern Oregon” by Tom Landis and Suzie Savoie (2016) is an excellent resource for selecting native plants for seasonal flowers and color.
Consider plant groupings within the community by their “sociability.” Some plants grow best individually or in small groups of 2-3 (Joe Pye weed, goat’s beard), while others are most effective in larger groups of 10-20 plants or more (yarrow, columbine, coral bells). Sociable plant communities support each other better, creating healthier, more resilient gardens and landscapes.
Remove non-native invasive plants such as vinca, Scotch broom and ivy; also, “edit” your garden by removing plants that are unhealthy or consume too much energy (water, sweat, tears).
Generate as many garden resources on site as possible. For example, use leaf litter from your garden plants for compost. Rather than bringing in soil from elsewhere, allow plant communities to adapt to the soil you have and improve the soil over time. Add to your garden naturally by allowing plants to self-sow. Build a swale to keep water, or a dry creek bed to channel water productively.
Reduce water consumption by switching to irrigation systems with slower emission, such as Techline drip tubes and Matched Precipitation Rotator sprinkler heads. One of the best ways to reduce water is by converting your lawn to a plant community.
If you are intrigued by the idea of designing resilient plant communities, don’t miss Morgan’s presentation, “A Different Way to Look at Landscape Design,” from 6-8 p.m. Tuesaday, Dec. 11, at the Southern Oregon Research and Extension Center, 569 Hanley Road, Central Point. The cost is $10 with preregistration or $15 at the door. To register, call 541-776-7371.
Rhonda Nowak is a Rogue Valley gardener, teacher and writer. Email her at Rnowak39@gmail.com. For more about gardening, visit her blog at http://blogs.esouthernoregon.com/theliterarygardener/.