Last month, I wrote about ground covers you could use for covering sunny areas in a rock meadow. This month, I’m focusing on ground covers for shady, rocky areas. Growing ground covers among rocks will not only add color, but will help suppress weeds.
Here are several shade-tolerant ground covers that will grow tall enough to cover river rock:
- Plumbago (Ceratostigma plumbaginoides). The first time I saw a photo of this plant, I thought that the brilliant, gentian blue flowers couldn’t possibly be as gorgeous in real life as they appeared in the picture. But when I later spotted this ground cover in bloom, I realized its flowers really are that spectacular. When you add deep green leaves and copper-colored seed heads to the mix, the plant is downright startling. And if that’s not enough, the plant’s leaves turn bright red in the fall. Because it spreads readily when regularly supplied with medium water, it’s a good choice for covering a shady rock meadow. In Colorado, plumbago will grow eight to 12 inches high and two feet wide or more. One thing to keep in mind, though, is that plumbago is very slow to green up. So don’t assume that you’ve killed it if it doesn’t start popping up with your other plants in the spring.
- Spotted dead nettle (Lamium maculatum). Years ago, a neighbor gave me some spotted dead nettle, which I planted in a moist, shady spot. Within days, slugs had decimated that plant. I haven’t grown it since. However, slugs are less likely to be a problem in a rock meadow, so I believe this plant would be worth a shot in these conditions. Dead nettle boasts lovely green leaves frosted with gray, and it grows 6 to 9 inches high by 2 to 3 feet wide. This groundcover likes medium moisture in well-drained areas. Although its flowers are relatively inconspicuous, dead nettle will produce clusters of tiny two-lipped white, pink or purple blooms in late spring or early summer. Popular varieties include Nancy, Wootton pink and orchid frost.
- Creeping Oregon Grape Holly (Mahonia repens). Talk about a plant you can just throw in the ground and forget—creeping Oregon grape holly will just take off on its own and envelop an area with its evergreen foliage. Once it’s established, it’s extremely drought-tolerant. I like this plant because, in addition to being outrageously tough, it’s always doing something. In the spring, Oregon grape sends up intensely yellow flowers, followed by clusters of deep blue berries, which mature in late summer. Although the berries are quite sour, they can be used in jellies. Then in the fall, the foliage turns reddish and provides a show throughout the winter. An individual plant will grow 12 to 18” high and about 24” wide, but it spreads quickly because of underground runners. If you want to control erosion, this plant is a great bet. The only down side is that Oregon grape’s leathery, spiny-toothed leaves tend to catch and hold onto litter.
- Sweet woodruff (Galium odoratum). This plant has the most adorable whorled leaves and fluffy, fragrant, white spring flowers. It grows about 6 to 12 inches high, and it spreads like crazy if it likes its environment. Although sweet woodruff prefers part to full shade and medium to wet conditions, I’ve grown it successfully in some dry, sunny spots. Pair this little darling with periwinkle (Vinca minor and Vinca major), which also grows 6 to 12 inches high and blooms at the same time as sweet woodruff. Seeing vinca’s purple blooms surrounded by woodruff’s fluffy white blossoms is a springtime delight.
- Rozanne cranesbill (Geranium ‘Gerwat’ Rozanne). I mentioned Rozanne in last month’s post about ground covers for sunny areas. But this versatile plant will grow successfully in part shade, as well. Rozanne’s cousin, bloody cranesbill (Geranium sanguinium) will thrive in both part shade and full sun, too. Whereas Rozanne generates large purple blooms all summer long, bloody cranesbill produces fuchsia blooms in the spring.