Published Aug. 13, 2017, in the Wyoming Tribune Eagle, “Covers of Color, ground covers good for replacing grass or gravel, and feeding bees”
By Barb Gorges
Gardeners consider ground covers to be short plants that act as living mulch, suppressing weeds and preventing erosion.
Your bluegrass lawn is a ground cover. Because it is so popular, its growing needs are well known. You can easily find someone to grow and mow it for you. Even simpler is growing native grasses—less water and much less mowing [search “Buffalograss” at www.CheyenneGardenGossip.wordpress.com].
However, when I surveyed the Laramie County Master Gardeners for their favorite perennial ground covers, a variety of short, flowering plants were listed requiring various amounts of sun and water.
All have big advantages over mulches like gravel or wood chips. Established ground covers out-compete weeds. Rock and wood chip mulches, on the other hand, eventually fill with weeds. Plants keep the ground around themselves cooler. Rock mulch makes an area hotter. Plants recycle carbon dioxide and make oxygen. Rocks and woodchips don’t.
A blooming ground cover offers more for bees and butterflies than rock, wood or a plain lawn. You can combine plant species in a mosaic, or in what’s being called a tapestry lawn by researchers at the University of Reading in Britain.
And you are in luck, late summer is a great time to find perennial ground covers on sale at local garden centers.
Plant now, a month or two before winter weather sets in, and you should see most of your investment sprout in the spring.
How close together you plant depends on how big a hurry you are in to get an area to fill in.
When comparing hardiness ratings, keep in mind Cheyenne is rated Zone 5, but many local gardeners look for hardier varieties rated down to the colder Zone 4 and even Zone 3.
Stonecrop, Sedum hybridum, is recommended by Catherine Wissner. There are many varieties of these succulents, but this one is only 4 inches high. It produces yellow flowers in late spring and early summer. It needs full sun, low amounts of water (after establishment) and is rated Zone 4.
Birdseye Speedwell, Veronica filiformis, is another of Wissner’s choices. This Zone 3 speedwell is only 2 inches tall. Fast growing, in some climates it can invade turf. Small blue flowers with white centers bloom mid-spring.
Turkish Veronica (or Speedwell), Veronica liwanensis, is one of three kinds of ground covers Martha Mullikin grows between flagstones. They all do well because they get the extra moisture running off the stone. This Zone 4 perennial becomes a blue-flowered carpet 1 to 3 inches tall in spring. It prefers sun with afternoon shade and a drier situation. Linnie Cough said hers blooms for two months. It is a Plant Select variety developed by the Denver Botanic Gardens and Colorado State University for thriving in western gardens.
Woolly Speedwell, Veronica pectinata, is a favorite of Susan Carlson. It is like Turkish Veronica, but the leaves are silvery instead of glossy. Both stay green over the winter.
Woolly Thyme, Thymus lanuginosus, and Lemon Thyme, Thymus citriodorus, are the other two forming mats over the flagstones at Mullikin’s. Both are good to Zone 4. Both like full sun and do well in xeric (dry) conditions. Lemon Thyme has the added benefit of being considered a culinary herb.
Red Creeping Thyme, Thymus praecox ‘Coccineus,’ listed by Tava Collins, is a red-flowering ground cover that doesn’t mind being stepped on a little. A Zone 4, it is drought tolerant once it has been established.
Mullikin is enamored with Dianthus ‘Tiny Rubies,’ Dianthus gratianopolitanus, which forms a 2-inch tall mat of leaves covered in pink flowers mid-spring to mid-summer. It prefers full sun and doesn’t mind the colder temperatures of Zone 3.
Barren Strawberries, Waldsteinia ternata, will remind you of strawberries, but the small yellow flowers (Mullikin has a variety with pink flowers) produce fruit considered inedible by people—no word on whether squirrels like them. A Zone 4, it likes full sun to part shade, and is somewhat drought tolerant.
Small-leaved Periwinkle, Vinca minor, Kathy Shreve said, “can take shade, and will grow under a limbed-up spruce tree if given enough water.” A Zone 4 less than 4 inches high, its periwinkle-blue flowers show up in May and early June. Mine, despite being in deepest shade, still plots to take over the world so I prune it when necessary.
Sweet Woodruff, Galium odorata, is another that does well in shade (it doesn’t like full sun), but I think mine would do better if I watered it more—it might reach the listed height of 6 to 12 inches. A Zone 4, its tiny white, fragrant flowers show up in May. Tava Collins said when it is stepped on or cut (or mowed), you may get the sweet smell of hay.
Hummingbird Trumpet, Epilobium canum ssp garrettii ‘Orange Carpet’ also goes by Zauschneria garrettii. Shreve reports it is a “great xeric ground cover, does not seed around indiscriminately, and hummingbirds really do love the orangey-red flowers. Also, it blooms in late July-August when most everything else has pooped out.” This is precisely when migrating hummingbirds passing through Cheyenne would appreciate it. A Zone 3, it is also a Plant Select variety.
Mary Ann Kamla recommended several plants including Creeping Jenny, Lysimachia nummularia, a Zone 3 with yellow flowers mid-summer. Mildly invasive, she keeps it contained with the edge of the patio.
Another that is doing well for Kamla is Soapwort, Saponaria officinalis. A Zone 3 with pink to white flowers, it appreciates water. Its leaves have historically been boiled to make a bubbly liquid soap.
Tava Collins is a fan of Spotted Deadnettle, Lamium maculatum. She grows two varieties: ‘Purple Dragon’ and ‘Pink Chablis,’ the names describing the flower colors. Hers bloom throughout the season, Collins said. The leaves are silvery with green edges. These varieties are Zone 4, but some others aren’t as cold hardy. Cutting back will encourage new blooms. The bumblebees love Lamium, Collins said.
Also on Collins’ list: Black Scallop Bugleweed, Ajuga reptens ‘Black Scallop.’ Ajugas are good ground covers in general. This one has leaves that look nearly black when grown in full sun. Early summer it has blue flower spikes. A Zone 3, it can be invasive in the garden.
Richard Steele simply grows clover instead of grass. It’s mowable, takes less water, he says, and it feeds his bees, which provide him with honey.
There are two ground covers I planted this year that Shane Smith, Cheyenne Botanic Gardens director, mentions in his garden tips at www.botanic.org. One is Creeping Phlox, Phlox subulata. A Zone 3, it should have no problem coming back next year, but since it prefers sunnier spots, I’ll see if it its pink and white flowers will develop in the shade.
The other is Snow-in-Summer, Cerastium tomentosum, another Zone 3, with silvery green leaves. Maybe next year it will give me more than one white flower. Patience, patience. Growing perennials is a long-term investment