"It's no longer enough for a garden to just look pretty. Every garden needs to do more and every garden matters," said Douglas Tallamy, a professor in the department of entomology and wildlife ecology at the University of Delaware.
Because of global warming and habitat destruction, he said, "today, gardens need to support life, sequester carbon, feed pollinators and manage water. It's a lot to ask, but it doesn't have to look messy and it may be the key to our survival."
For many people who aren't sure what they can do about climate change, home gardens provide an opportunity to make a palpable difference.
That sense of purpose is creating a change in garden esthetics, with a more natural look and more emphasis on drought-tolerant and wildlife-friendly plants.
"It's one of the few things an individual can do to mitigate climate change. The cumulative impact on the environment is huge, plus it's easy, affordable and fun," said Ann Savageau, who ripped out most of her lawn in drought-parched Davis, California, a year ago and replanted with desert grasses and other native plants.
"The increase we've seen in pollinators, butterflies and birds at our house is really exciting, and we reduced our water usage by two thirds," she said.
Whereas there used to be enough land for wildlife and humans to exist separately, it's become essential that we share habitats, Tallamy and Rick Darke argue in their book, "The Living Landscape: Designing for Beauty and Biodiversity in the Home Garden" (Timber Press, 2014).
"Unless we share our space with nature, the plants on which bees, caterpillars, butterflies, birds and other wildlife depend will not survive," Tallamy said.
Earth-friendly gardens consist mostly of native species, on which local wildlife depends, experts say.
"Gardening for wildlife, especially birds, is really the hot thing now in horticulture and gardening. The trend is toward naturalistic garden design, with native plants. It's a High Line kind of a look," said Kristin Schleiter, associate vice-president for outdoor gardens and senior curator at the New York Botanical Garden.
The High Line, the New York City park and garden which runs along a strip of old elevated track, "does symbolize a newer esthetic in purposeful, naturalized gardening," said Tom Smarr, its director of horticulture.
About half the plants are natives and the other half are self-seeded species, which require relatively little maintenance and water. "There's way more forgiveness and durability about it," he said.
"A lot of people have totally been inspired by the wild look and have tried it on their own at home," Smarr said.
A few specific ways that home gardeners can go easy on the planet:
PLANT AN OAK TREE
Oaks sequester lots of carbon, have enormous root systems that help manage water and, according to Tallamy and Darke, are fantastic at supporting wildlife. "There are 557 species of caterpillars in the Mid-Atlantic states, and they're all bird food. The birds eat all the caterpillars to support their young, so you don't need to worry about defoliation."
FEED THE POLLINATORS
Tallamy warns that without pollinators, 80 per cent to 90 per cent of all plants would be lost, and that gardeners should focus on plants that feed the estimated 4,000 species of native bees. Pollinator-friendly gardens feature a sequence of native flowering plants, so that from April through September something's always blooming. Mountain mint, sunflowers, native holly, sweet pepper bush and goldenrod are all great for pollinators, Tallamy said. Further west, blazing star and milkweed are good choices. Schleiter said that early spring can be especially tough for bees. For early bloomers, she recommends Lyndera, a native bush with great fall colour, and also dogwood.
MINIMIZE LAWN, CONCRETE AND NON-NATIVE ORNAMENTAL SPECIES
"Around 92 per cent of our suburban lots are lawn, and that's the worst you can do," Tallamy said, adding that concrete seems to be our "default landscaping" and ornamental Asian plant varieties have little to offer native wildlife.
"In the typical American yard, 80 per cent of the plants are from China. That's not a functioning eco-system," he said.
Even apartment dwellers can help, by planting native species on roofs and terraces.
Schleiter said: "Really think about the amount of chemical that's put on our lawns. If you're not using all of your lawn, just let the grass grow out and maybe put in some native perennials. It all adds up."
"If you're planting a garden for bees and butterflies, don't use pesticides that will kill bees and butterflies," warned Schleiter. "It sounds obvious, but people do it all the time. You have to be extra sure that when you buy a plant at the nursery, it hasn't been sprayed with any pesticides. Nurseries do it a lot and you need to be extremely careful."