Van Dycks

Groundcovers are the workhorses of the garden. They can form a beautiful living mulch beneath trees, shrubs, and perennials; they can anchor soil on a slope, and some of them are so lovely they can be used as specimens or focal points in garden beds and borders. Most groundcovers are called that because they spread, sometimes slowly, often rapidly, to cover a bit of ground. Once in awhile, a groundcover can escape into the lawn or into other areas, where their innate vigor sets them up to out-compete your favorite perennial planting. Ooops! It pays to keep an eye on groundcovers, so you don't get an unfortunate surprise.

One of my favorite sights in spring is at a local arboretum, where a noxious invasive weed has been allowed to form carpets of blossoms under the trees. The gardeners tried several years ago to eradicate the weed, but visitors complained that they missed seeing it, so they have now allowed it to come back. It looks quite cheery for about three weeks and then over the next few weeks, goes dormant and disappears – only to reappear more aggressively than ever the following spring. This is actually a cautionary tale. The gardeners at the arboretum are professionals and have made a conscious decision to let the public have its way. However, they must be extra vigilant to stop the weed from encroaching further into the landscape. You may not be a professional gardener, but it is still important to keep an eye on anything you plant – groundcover or not. It has unfortunately turned out sometimes that a newly introduced plant will have invasive tendencies that weren't apparent until people in different parts of the country began planting it. What is invasive in one part of the United States may not be so in another part.

There are, of course, many groundcovers that spread slowly and can easily be kept in check. One of my favorites is Epimedium rubrum, because it does so well in dry shade under trees and shrubs. It has dainty, heart-shaped green leaves that are tinged with red when they are new. Later, in the fall, the foliage turns a coppery red and yellow. That's the best type of plant – one that give you more than one season of interest. The bonus with epimedium is the lovely flowers in mid-spring. They are shaped like tiny, ruby-red bishops' hats and are held above the foliage. Charming! Epimedium will eventually spread over a considerable area, so you will always have some to share with the friends who with ask, admiringly, what that lovely plant is. Low growing, 10 to 15 inches tall, it is hardy in zones 4-9.

Periwinkle, Vinca minor, is a perennial favorite. Its sweet, purple-blue flowers have given their name to the color, periwinkle blue – a fashion favorite. This is a versatile ground cover, able to tolerate everything from quite a bit of sun to deep shade without a lot of fuss. The dainty flowers bloom in May-June and are set off admirably by the small dark green leaves that are evergreen in the milder parts of its range. It spreads quickly by rooting where the leaf nodes touch the soil. It is very low growing, 4 to 10 inches tall, and hardy in zones 4-9.

Creeping phlox, P. subulata, is an excellent groundcover for sunny, sandy and dry areas. Its foliage is evergreen and the delicate-looking flowers literally cover the plants in April-May, in spring-like shades of pink, blue, white and red. It can spread quickly, is very low-growing at 4 to 6 inches tall, and is hardy in zones 2-8.

Cote d'Azur pinks, Saponaria ocymoides, has a similar look to creeping phlox but blooms in June-July on semi-evergreen foliage. It is an excellent, easy-care groundcover with a trailing habit that is perfect for covering banks and spilling over walkways, terraces and low walls. It spreads quickly, is very low-growing at 4 to 6 inches tall and is hardy in zones 2-10.

Lamium 'Anne Greenaway' has beautiful foliage with bonus flowers in April-June. The leaves are dark green with “toothed” chartreuse edges and silver streaks down their centers. The flowers are purplish-mauve and contrast smartly with the leaves. This is a very vigorous, low growing (4 to 6 inches tall) groundcover; each plant will spread some 18 inches wide. It is hardy in zones 4-8.

Chameleon flower, Houttuynia cordata, is not known for its flowers, which are small, white and bloom in June-August, but for its dense, colorful foliage. Though it can take some shade, the color is brighter the more sun it gets. This is a very vigorous groundcover, spreading wider each year. It grows 6 to 9 inches tall and is hardy in zones 3-8.

There are lots of plants that you might not immediately think of as groundcover plants. One is Potentilla 'Fire Flames', a vigorous, long-blooming perennial with brilliant red flowers with darker centers in June-September. It makes an evergreen groundcover in the warmer part of its range and works just as well in a perennial border or rock garden. It grows 15-24 inches tall and is hardy in zones 3-7.

One of my favorite perennials, hardy cranesbill geraniums, are models of low-maintenance and not only perform beautifully in the perennial bed in full sun to partial shade but also make exquisite groundcovers. I've grown them for years and they have given me nothing but pleasure. They need no particular care except to cut the taller ones back after flowering, so that the foliage remains upright until frost. They are easy to divide to use in other parts of your garden or to share with friends. Many have a strong flush of bloom in early summer and then sporadic flowers until late summer, when there is another flush of bloom until frost. Even when they are not in flower, however, their foliage is quite lovely, dark to medium green with varying sizes and fancy shapes. The plants are hardy in zones 4-8 and never seem to have problems with pests or diseases. They are, in fact, just about perfect!

I am particularly fond of Geranium sanguineum 'Album'. It has delicate, ferny foliage and the most delightful white blossoms in June-August. It grows 8-10 inches tall and expands quickly. It has a beautiful cousin, G.s. 'Striatum', which blooms in May-September with pretty pink flowers delicately striped in red. There are many other hardy geraniums that are equally useful and beautiful: G. himalayense 'Plenum', also known as Birch's Double, grows to 15 inches tall and has the most lovely rose-pink double flowers in May-September over bolder, but very beautiful foliage. G. platypetalum grows to 24 inches tall and blooms in May-August with gorgeous deep violet-purple flowers. G. cinereum 'Ballerina' is quite small at 5-10 inches tall, and has purple centers with dark veins radiating out into lilac pink flowers. It is closely related to G. c. 'Purple Pillow', which grows 6-8 inches tall and has reddish purple flowers with darker veins. G. pretense 'Splish Splash' grows 25-30 inches tall and produces pure white blooms in June-August that are streaked with lavender blue. G. wallichianum 'Buxton's Variety' grows 10-15 inches tall and blooms in July-September with large blue flowers with white centers and dark veins.

The hybrid geraniums are equally exquisite: 'Patricia' grows 20-25 inches tall and has vivid cyclamen red flowers in June-September. New this year is 'Orion'. At 18 inches tall, it has large, saucer-shaped flowers of bright blue in May-June. 'Johnson's Blue' has been a gardeners' favorite for many years; it grows to 20 inches tall and produces cup-shaped blue flowers in May-September. Last, but far from least is 'Salome'. It grows to 12 inches tall and has violet flowers with dark centers and purple veins from July-August. As an added bonus, 'Salome' has very attractive light green to chartreuse foliage that sports a marbled pattern.

Another perennial that can be used as a groundcover is coral bells, Heuchera sp. Coral bells are great in both sunny and shady sites (it will need more water in full sun) and are also easy-care plants that seem to have no serious pest or disease problems. They will expand slowly, so a massed planting is best. Many have beautiful flowers, but coral bells are grown more for their gorgeous foliage that come in plain green as well as some outstanding multi-colors. One in particular is truly awesome: H. 'Amber Waves' has ruffled amber-gold foliage. You may not even notice the light rose-colored flowers in June-July, as you watch the leaves change color all season. Fabulous!

And, probably one of the most popular perennials for shady areas (some can take some sun when given extra moisture). I am speaking, as you have probably already guessed about hosta. There are so many excellent hostas, that it is hard to single out any particular one. While you might not immediately think of them as groundcovers, they perform admirably in that function as they slowly expand. Prone to few diseases, hosta does attract slugs. Many gardeners have managed to outwit their resident slugs with a variety of methods, from getting them drunk on beer to pouring salt on them to using crushed eggshells on the ground around the plants and, if all else fails, resorting to slug bait. Hosta plants are absolutely worth the trouble, though some gardeners consider the slug wars high entertainment! If you're up to the task – and I bet you are – try massing them and even if the ground you are trying to cover is fairly small, there are even dwarf hosta. How can you possibly resist?

And now, here are a few words about shade. As you have no doubt noticed, all shade is not created equal. Flowering plants that need shade really want “dappled” shade. That means the tree canopy overhead lets sunshine though during some part of the day. If your tree canopy doesn't let any or very little sun through, you will need to call a certified arborist (a tree specialist) for a consultation. Arborists are trained to diagnose and treat tree problems – one of the techniques they are taught is how to thin a tree's canopy to let more sunshine in. This benefits the health of both the tree and anything growing under it.
There is another type of shade that is very difficult for plants to tolerate – dense shade cast by a building, fence or other structure. In that case, flowering plants are probably not going to do well. You can concentrate on non-flowering groundcovers, such as ferns or caladium and try to bring in reflected light with white or mirrored surfaces. Some of the most interesting gardens I have ever seen are ones in which the gardener has had to come up with unique and creative ways to bring more light into the planting areas.

Sometimes, the dense shade cast by a structure lasts only for a few hours in the morning or afternoon, i.e., the northeastern or northwestern side of the structure. The term “full sun” refers to six or more hours of more or less direct sunshine a day. As long as the dense shade lasts only a short time, you can plant flowers that need full-sun, bearing in mind that in cooler zones morning shade is more desirable and in southern climes afternoon shade is best, so the plants don't get “sunburned”.

In case you are wondering why I bring all this up, it's because most plants that are considered groundcovers require some shade. Remember that that means dappled shade, or deep shade only a small part of the day, and you absolutely can't go wrong.

So, let's go out and cover the ground!