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FeedLow-Down Perennials
Compose a low-maintenance garden floor with groundcovers
By bonnie blodgett
Photo by Judy White / www.gardenphotos.com
These designers are usually making a point about three-dimensionality in the garden when the term “understory” comes up. Though it is not in my dictionary, the Internet produced 120,000 entries in 0.18 seconds when I Googled the term. The first 10 had to do with gardens. Understory refers to the level at which smaller ornamental trees and tall shrubs proliferate, and is not to be confused with what I think of as the second and third stories populated by the towering shade trees—oaks, elms, maples, and the like.
Maybe because I’m not a garden designer, my attention is easily diverted from the treetops to the floor. This is where the lowly groundcovers dwell. One talented garden designer I know tells me he leaves the floor for last because he wants to see how the larger plants—the perennials and the understory trees and shrubs—will fill out. Groundcovers are added to fill the “holes” once the important plants are established. Until then, the floor covering is a layer of mulch.
Since groundcovers, too, take a while to get going, and since mulch is expensive, and since (I think) what crawls around on the ground is every bit as aesthetically important as flooring is to a room, I plant groundcovers right along with the other plants. If they get too aggressive, I pull out the overachievers by the roots. This is easily done with most groundcovers, as they tend to grow sideways, sending out shoots that lay claim to new territory by rooting where they creep. Most groundcovers are shallow rooters and easily dislodged. I avoid the more tenacious types in the first place.
The ultimate low-maintenance flooring material for sunny areas (unless you’re a perfectionist) is, of course, grass. A lawn is calming to the eye and inviting to the foot. Among the most popular of the other sun-loving ground covers are moneywort, thyme (all varieties), and sedum (the ground-hugging, not the upright, types).
On my sunny front terrace, thyme grows between the flagstones and directly on top of them. Once a summer I find myself on all fours pulling up the aromatic herb by the handful to uncover just enough of the hardscape to remind myself that I made a terrace here once upon a time. It was supposed to be an intricate composition of brick, gravel, and slate flecked with tidy clumps of herbs, not buried entirely beneath them.
Thyme will spread quickly as long as it has good drainage and lots of sun. I combine several varieties so one is usually blooming and make sure to protect the more delicate ones like woolly thyme from being overrun by the roughnecks. If you like to cook, look for culinary thyme, which comes in many flavors including lemon.
Sedum is one of my favorite plants in any category. I grow S. spurium ‘Dragon’s Blood’ on a stone wall where it gets full sun and nestles fetchingly in the cracks before spilling over the edge. Sedum has rubbery leaves in several sizes and colors from pale green to bronze. Its relatively insignificant flowers range from yellow to coral to bright crimson. ‘Limelight’ sedum has chartreuse leaves and tolerates some shade. It is the latter feature (not the trendy leaf color) that lets it into that most exclusive clique of groundcovers that are both attractive and great at multitasking.
Dry and dense shade conditions require groundcovers with tougher constitutions. If you have a large area that would be perfect for grass were it not for that shallow-rooted maple blocking the sun, choose a groundcover that doesn’t need regular watering or a rich soil. Lysimachia nummularia ‘Aurea’ might work, and its golden color not only makes it less rampant than its deep green sibling but also really lights up dark spaces. Euonymus fortunei ‘Coloratus’ (purple wintercreeper) and Vinca minor (lesser periwinkle) are also aggressive growers with a trailing habit. Pachysandra is a staple under shallow-rooted trees in places like Washington, D.C., but here on the tundra it needs winter protection. Common bugleweed might adapt if it gets plenty of water in the early going.
What crawls around on the ground is every bit as important as flooring is to a room.
If you’ve tried these with no success, the fail-safe solution is Aegopodium podagraria, AKA goutweed. With its silvery green leaves, it’s a looker; too bad it doesn’t know when enough is enough. Contain it within metal or vinyl edging—unless you don’t mind an all-goutweed garden and are looking for a way to make your neighbors stop speaking to you.
Truth is, most groundcovers can become invasive if they love your soil and light and aren’t supervised. Ajuga (bugleweed) gets a bad rap in this regard. In my garden it stays put, though I grow only the more decorative cultivars like ‘Catlin’s Giant’, ‘Chocolate Chip’ (a dwarf), ‘Metallica Crispa’, and ‘Bronze Beauty’ that are a bit less aggressive. The dark, rippled leaves of ‘Metallica Crispa’ are stunning planted in masses, but the plant insists on regular moisture and excellent drainage, a tough combination in my garden and probably why the two I brought home from a specialty nursery three hours away both vanished in a week. Reportedly, if it gets what it wants (whatever that is), it can become a pest (I’ll believe it when I see it).
Lamium is, in my opinion, the most underrated groundcover on the planet. I’m not talking about the yellow-flowering ‘Hermann’s Pride’. That’s false lamium (Latin name: lamiastrum, or “resembling lamium”). I’m talking about plain old everyday dead nettle. It thrives even in deep shade, and its silvery foliage blends with everything.
I’m especially fond of the lavender blooming L. maculatum ‘Beacon Silver’. This plant happens to be the most common dead nettle in U.S. commerce. If banality bothers you, try the cultivar with white flowers (L. album) or, if you’re truly into the unusual, ‘Beedham’s White’, which has chartreuse foliage.
Lamium doesn’t much like dry shade, but if you keep it reasonably moist it will form lovely soft clumps, scamper around, and even self-seed here and there—always delightfully, since it seems incapable of clashing with other plants and makes most of them look far better than they did alone. It is easily uprooted if you don’t like where it lands. This can be disappointing in spring when you rake off the winter leaf cover and pull up all your lamium with it. Better to cover it lightly, pray for snow, and, come spring, pick off those dead leaves by hand.
Of course there are dozens of excellent groundcovers I haven’t mentioned, but I’ve included those I rely on to erase eyesores and planting mistakes. Like fine flooring, groundcovers also offer cohesion and rich texture—qualities that regrettably are often lacking in a garden, even one whose understory is perfectly composed.
BONNIE BLODGETT EDITS THE GARDEN LETTER: GREEN THOUGHTS FOR THE NORTHERN GARDENER AND IS WRITING A BOOK ON SMELL.
11 ISSUES (1 YEAR)
