Expert Advice on Gardening Amid Climate Change
Ideas for a resilient garden
If you’re confused about what to plant nowadays, you’re not alone. Rapidly shifting climate conditions, from drought to floods and fires to ice storms, have many of us rethinking our approach to gardening. I asked industry experts across the country to share their perspectives, and several themes emerged about stewarding beautiful, resilient landscapes in the years ahead:
1. Be your garden’s detective
“Gardeners need to keep learning and being curious. If a plant is struggling, start acting like a detective,” said Brooke Edmunds, Oregon State University extension agent and Master Gardener lead in the state’s Marion and Polk counties.
“Gardeners attuned to their conditions will continue asking foundational questions,” she said. “Is it something with the soil? Is it not in quite the right spot? Is it getting enough sunlight? We all have to adapt.”
2. Find and use the garden’s microclimates
As we try to lessen our impact on the planet and garden with fewer inputs and greater purpose, finding the right plant for the right place has never been trickier or more important. The sun, wind, drainage and soil can change within a few feet in your garden. Observing microclimates—like where your spring bulbs bloom first, which spots hold water and which get scorched in the afternoon sun—is key to success. Elevated sites, including raised beds and the tops of berms, tend to be warmer and windier and can dry out quicker. Beds against sunny walls can offer some cold protection, while gardens at the base of a hill may sit in a frost pocket.
The most resilient gardens pair plants to the existing soil, rainfall and drainage conditions, thereby avoiding the need for copious soil amendments, fertilizer and supplemental water. For ideas, notice which plants in your area are thriving despite recent challenges, and compare notes with local gardening groups.
3. Hardiness zones aren’t everything
In November 2023, the United States Department of Agriculture’s Plant Hardiness Zone Map got a major makeover, placing more than 50 percent of the country a half-zone warmer. Zones tell you the coldest temperature limit to expect on average. The latest map, developed in collaboration between the USDA and Oregon State University's PRISM Climate Group, also adds two new zones: 12 and 13, where the average low temperature falls between 50 and 60 degrees or 60 and 70 degrees, respectively.
It's important to note that the shift reflects climate changes but also deeper data, culled from 30 years of records. In comparison, the 1990 map used 13 years of records. The new map also reflects microclimate data points calculated on a location’s degree of elevation and proximity to bodies of water.
Gardeners will do a happy dance at the prospect of overwintering perennials they previously understood as borderline to their zone. On the flip side, plants like peonies, tulips and many fruits require a minimum number of “chilling hours” to bloom and fruit successfully. In warmer winters, they may not fare as well.
However, in choosing plants, cold hardiness is only one variable to consider. Ray Larson, the curator of living collections at Seattle’s University of Washington Botanical Gardens, is expanding his options, looking at Southeast-adapted crapemyrtles (Lagerstroemia) and magnolias and at plants from high elevations in northwest California and southern Oregon that can take both some cold and heat, for instance. He trials experimental varieties in containers for a season before planting.
This strategy extends into the plant industry, as well. Grower Proven Winners is taking a multistemmed approach to plant selection, seeking compact natives, waterwise plants and those that can tolerate extreme conditions.
“We look to breed with genera that are more tolerant of a wide range of temperatures. To home gardeners, this would manifest as a wider range of hardiness zones—such as USDA Zones 3 to 9 (instead of) 6 to 9—and soil conditions, like some tolerance to both wet and dry soils, at least for short periods,” explained head breeder Megan Mathey, citing black chokeberry (Aronia melanocarpa) as an example.
Disease resistance is coming to the forefront, she added, specifically “fungal leaf-spot diseases, which proliferate when humidity and rainfall are very unpredictable or intense.”
Katie Tamony, chief marketing officer for Monrovia, said, “We recommend thinking about fostering climate-appropriate diversity in your planting choices.” The company is looking at Southwest natives like white sage (Salvia apiana) and desert willow (Chilopsis linearis) for their heat tolerance and drought resistance.
“We are selecting more drought tolerant varieties for colder zones, because we can see that areas from Utah to Minnesota are experiencing drought conditions,” she added, highlighting Dazzle Rocks sea lavender (Limonium gmelinii ‘ST3 10’)) as a drought-adapted choice appropriate for Zones 5 to 11 that attracts pollinators and thrives in tough soil.
4. Put environmental vitality first
Designers and curators are looking to create dynamic landscapes that improve, rather than take from, the environment, with biodiversity as the primary goal.
“This question is at the forefront of every project: How can we make our work more resilient, require fewer resources and be there for the future to sustain us and wildlife?” shared Claudia West, a principal of Phyto Studio in Arlington, Va., and the co-author of Planting in a Post-Wild World.
“Our winters are becoming milder and our summers drier, so we are shifting to species that can handle those specific conditions, maybe from the South or Southeast and usually higher elevations,” she said.
West would prefer a locally adapted native plant to a climatic analog, however, pointing out that “even though a plant from Chile might be perfectly hardy here, it is not connected to our local ecology.” Accordingly, her firm searches for local ecotypes of plants.
“You can’t plant a Florida-bred white oak (Quercus alba) in Canada and assume it will be fine,” she cautioned, adding that species selection is only one piece of the puzzle, though.
“How we cover the ground is just as important,” she said. “Creating as much biomass as possible is really important. Both private and public spaces, like parks, are chronically under-vegetated. This is an international phenomenon.”
She’d like to see less mulch, more ground cover and more plants in general to support diverse ecosystems. Landscape architect Martin Harwood, the technical director of SCAPE, a design firm headquartered in New York City, would concur.
“Maybe one of the most important factors is to support species diversity and native wildlife—insects, butterflies, moths and birds,” Harwood said. “We try to think of our landscapes as not just pretty places but ones that can be ecologically productive as well as coherent.”
He suggested home gardeners can examine successful plant communities, from trees to groundcovers, in their yard or nearby it and bolster these by adding plants that support the insect and bird species present.
He encourages adherence to “the 10-20-30 rule.” If you count all the plants in a planned landscape, a particular species should total no more than 10 percent; a genus, no more than 20 percent; and a plant family, no more than 30 percent. Limiting numbers in this way will help slow opportunistic pests and pathogens from taking hold.
Greg Paige, director of horticulture for the JC Raulston Arboretum in Raleigh, N.C., similarly cautioned against the dangers of falling in love with a few “easy” plants, which can create monocultures, fueling stress, pests and diseases.
“These wide swings of climate stress plants out, and when you have a plant that’s over-sold or planted incorrectly, they are going to be highly susceptible,” he said. “All of these things are interwoven.”
To preserve your plantings’ vitality and biodiversity, these experts encouraged thoughtful care: avoid pesticides, cover the ground with plants, group plants with like needs together, weed out invasive plants, water deeply and less frequently and leave spent stems up and fallen leaves down in the winter as habitat.
