In an age of environmental woe — climate change, habitat loss, threats to beloved pollinators — should we change the role and the look of our gardens?

You won’t have to read many pages of a new book, “The Living Landscape,” to get your answer. Authors Rick Darke and Doug Tallamy argue that our residential landscapes are surprisingly barren places that could be transformed into oases for plants, animals and, ultimately, ourselves.

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Darke is a well-known garden writer and ecologically minded plantsman, and Tallamy is an entomologist whose influential 2007 book “Bringing Nature Home” established the utility of native plants in a greater biosphere.

The new book is not simply another call to use native plants, although it leans heavily on indigenous flora. It is rather a manifesto for increasing the diversity of plants we grow.

As we enter the prime season for reworking the garden and planting afresh, this is a timely issue. Darke and Tallamy argue that with a sufficiently rich mixture of plant species comes an interconnected world of mammals, birds, amphibians, reptiles and insects — a spider’s web of life spun by the gardener.

Why should we care?

Darke’s aerial photographs bring home what may not be obvious at ground level. Development patterns squeeze out life: The city is a canvas of asphalt, concrete and flat roofs. New housing subdivisions in outer suburban and rural areas are bereft of much plant life and are more likely to feature oceans of lawn and rows of arborvitae. Even the older, leafy inner suburbs could be so much more.

Home gardens, once thought of by ecologists as a way to provide corridors for fauna between habitats, now must become contained habitats themselves, Tallamy says.

“Why do residential landscapes suddenly have to shoulder this new ecological responsibility?” Tallamy writes. “Quite simply, the natural world is now so fragmented that any given piece is no longer large enough to sustain most of the species within it for very long.”

In an interview, he said the idea of ecological gardening has taken off because it offers a tangible way for people to address wide-ranging environmental crises. “People love to feel empowered,” he said. “If you put an oak tree in your yard, you see the difference.”

Flora in natural areas fill their own niches — shade trees form part of the canopy over lower-growing trees and shrubs, and the understory plants, in turn, shelter an herbaceous level of such things as ferns, bluebells, trilliums and may apples. All this vegetation feeds the living soil — if the fallen leaves are not neatly removed. This natural layering cries out to be replicated in the home garden, Darke says.

From a purely aesthetic standpoint, I would add, it’s clear that most gardens do not reach their potential. We do not plant intensively enough or paint the ground with bold sweeps of plants. There are few residential landscapes that couldn’t accommodate more plants, and many established gardens — including my own — have corners where overgrown shrubs and the like could be removed to create a fresh montage that would be more attractive and more welcoming to other living things.

As Darke points out, we have too much area given over to lawn and too many garden beds covered in mulch rather than in plants.

“Everybody is on this kick with mulch, and with mulch you don’t have a lot of biological processes going on,” he said in an interview.

After reading the book, I have an urge to bring more ground covers into my mostly shaded garden, particularly woodland phlox and creeping phlox, white wood aster, maidenhair and Christmas ferns, and the much underused woodland stonecrop, Sedum ternatum. Darke suggests interplanting the stonecrop with Virginia bluebells, which put on a fine show in April and then recede as the stonecrop fills in.

The knack is to plant in sufficient numbers to form bold drifts whose leaf colors and textures create a visual structure and, as such, are more important artistically than fleeting blooms.

How do you pay for all these plantings? This isn’t a central question of the book, but the authors answer it in a roundabout way. I’ll add my take on it: You buy the smallest plants you can find — perennials in four-inch pots rather than one-gallon containers, shrubs two to four feet instead of six to eight feet, and one-inch-caliper trees instead of three-inch monsters. Given the correct soil and light conditions, small plants establish better than bigger ones and soon catch up in their growth rates. The payment for this thrift is patience, but you don’t have to wait as long as you might think to see results. Tallamy planted the acorn of a white oak in the driveway circle of his 10-acre property in Oxford, Pa. In 13 years, the tree grew to 20 feet. (Start acorns in pots away from friendly squirrels.)

Another way to spend your garden budget on plants rather than hardscape is to stop paving over paradise. Upgraded landscapes today seem to be measured in how many pavers you can install, for driveways, patios and walls. Darke urges a return to softer, greener spaces that are delineated by plants rather than concrete.

In his own 1.5-acre garden in Landenberg, Pa., Darke’s outdoor spaces have been composed with carbon-based life forms. “Dry-laid stone is employed for areas that must withstand very heavy use and a few low wooden screens have been built for privacy,” he writes, “but all other paths, surfaces and spaces have been constructed entirely with living materials: grass, moss herbs, shrubs and trees.”

Environmentally, such a landscape is going to be better at slowing storm water, filtering pollutants, cleaning the air and shading our living spaces.

Tallamy said that if you regard your landscape creation as a long-term hobby rather than an instant installation, you can plant at your pace using small plants or even seeds. “You can do it for practically free.”

Not all plants, even native ones, are as effective as others in sustaining wildlife. For Tallamy, a key attribute is the plant’s attractiveness to caterpillar species. The more caterpillar types that live in a tree, the more species of bird they feed. As iconic as the flowering dogwood is, other dogwoods do more for wildlife; namely, the alternate-leaf dogwood and the shrubby gray and silky dogwoods. The standout tree species is the oak, for its caterpillar habitat (an amazing 557 species) and acorns for mammals and birds. Tallamy commends 11 oak species for our region, including the swamp white oak — perfect for poorly drained sites — and the chestnut oak, which Darke particularly likes.

“By planting our landscapes with productive plants, we can create diverse, stable and balanced food webs that meet our own ecological and cultural needs while enabling life around us,” Tallamy writes. Who would argue with that?

Six underused plants that will give long-term enjoyment to gardeners in the Mid-Atlantic:

Layering plants — putting them in their natural order with other plants — is essential to creating a garden of interest to people and of value to wildlife, says ecological landscape designer Rick Darke.

We asked him to suggest half a dozen underused plants that with a little care and correct placement will give years of easy enjoyment to gardeners in the Mid-Atlantic region.

1. Common witch hazel

Asian hybrids are more commonly planted for their garden traits, but the native witch hazel (Hamamelis virginia) forms a large, multi-stemmed shrub that regenerates from suckers. Asian witch hazels bloom in late winter, but the native species displays its yellow flowers in late fall, sometimes before leaf drop.

Although it can grow to 15 feet untamed, the witch hazel’s suckering habit allows the gardener to remove older stems to keep the shrub at a smaller height and breadth.

Darke: “It’ll take extremes of dryness and saturated soil; it’s free of pests and reliably vase-shaped, which makes it the perfect choice for creating light shade in a sitting area.”

Sources: Forest Farm (541-846-7269, www.forestfarm.com), Hill House Farm & Nursery (540-937-1798 www.hillhousenativeplants.com).

2. Pawpaw

Pawpaw is an attractive fruiting large shrub or tree and is the host plant of the zebra swallowtail.

It can work in many roles, although fruit production falls off in shadier locations. Pawpaw (Asimina triloba) can be used as an understory shrub in the woods, as an edge plant between shady and sunny beds or as a freestanding tree in the lawn. You need at least two for fruit production. Varieties have been developed for better fruit quality.

Darke: “You could even use them to line walkways almost as an allée. The fall color [golden yellow] is outrageous.”

Sources: Edible Landscaping (434-361-9134, www.ediblelandscaping.
com
), Forest Farm, Hill House Farm & Nursery.

3. White wood aster

Unlike the late-summer asters of the meadow, the white wood aster (Aster divaricatus) is a low-growing shade plant that makes a beautifully textured ground cover. It blooms white in late spring, although its real value is its dense green foliage. Use it instead of mulch.

Darke: “It’s a living, weed-suppressing ground cover that is deer-proof, durable and versatile.”

Sources: Niche Gardens, Forest Farm, Hill House Farm & Nursery.

4. Christmas fern

This is a medium-size native fern that remains green in winter, when its fronds lie flat. This is a useful, highly textural and deer-proof ground cover for areas of dry shade. It’s known botanically as Polystichum acrostichoides.

Darke: “Use it to define pathways. It’s a fern with seasonality; in the spring the new fronds are chartreuse. Also, it’s a plant that will outlive you.”

Sources: Watermark Woods (540-441-7443, www.watermarkwoods.
com
), Niche Gardens (919-967-0078, www.nichegardens.com), Hill House Farm & Nursery.

5. Mountain mint

This perennial grows in partial shade or sunny conditions and when massed provides a striking and aromatic block of color and texture. Several species are gaining in popularity, but Darke commends the more assertive mountain mint species Pycnanthemum muticum for new plantings in disturbed soil, to squeeze out weeds and invasives. The foliage is gray and topped in summer with white blooms.

Darke: “A fabulous plant for pollen and nectar services: loaded with all kinds of butterflies and hynoptera.”

Sources: Watermark Woods, Hill House Farm & Nursery.

6. Pinkroot

Firmly in the realm of nerd plants, the pinkroot is a native perennial (Spigelia marilandica) with showy, upright clusters of red tubular flowers that draw hummingbirds in early summer.

It is also one of those plants that resents disturbance and doesn’t lend itself to conventional container planting. It is best grown from seed or as a young plant, and, once established, it will spread by highly scattered seed. The gardener, at that point, merely removes plants from unwanted spots.

Darke: “It’s promoted as a rarity that needs shade and moisture. We have seen that it is easy to naturalize.”

Sources: Plant Delights Nursery (919-772-4794, www.plantdelights.com), Niche Gardens, Watermark Woods, Hill House Farm & Nursery.

More from The Washington Post:

Gardening lessons learned from the farm

Where have all the butterflies gone?

The U.S. National Arboretum is breathing new life into an old plant

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