What makes a groundcover? Plants that can tolerate sunny dry soils, wet soils, windswept sunny/shady slopes, or shaded areas, and will spread fairly quickly, help choke out weeds, and preserve moisture.
Groundcovers are usually a single type of thick foliaged plant, quick growing, tough, can either be only several inches to several feet tall, and depending on the plant, will take some light traffic. Once established, groundcovers will also help cut down on the amount of weeding needed.
Groundcovers are used under shade trees and north sides of houses where regular grass or plants won’t survive, on lightly traveled areas, slopes where erosion from wind, rain and snow have left an unsightly spot, or areas where grass and its requirements, have become a problem.
Though groundcovers are a great help, and many sing their praises, there are a few things to consider when planning to use them. Unless you plan to go out and purchase several hundred plants to completely cover a given area immediately, patience will be needed, as it will take two to three years for the area to be covered. This will mean that diligent work will be needed to ensure that no weeds take hold in the area. You will of course, start out with a well-cleared spot, and then make sure that any weed that starts is immediately removed. Some watering is needed until the young plants are settled in and growing. If the plant material is small and single rooted, eg. Ajuga, then about 6" (14 cm) between each plant will be about right. When the plants are larger, eg shrubs, daylilies, then anywhere from 1 ft. (30 cm.) to 3 ft. (1m.) would be the placement required. Whatever you use, by the third or fourth year, the plants will need to be divided, so that they will not die out from overcrowding. Dividing of the plants will also encourage the smaller plants to grow, the divisions can be used to fill in if there has been winterkill. Propagation can also be accomplished, by layering some plants, and taking cuttings for rooting, from others.
Be very choosy as to which plants you select for certain areas, eg, goutweed, lily-of-the-valley or snow-in-summer, should never be used where their growth can not be controlled. They will take over any flowerbed, wander out into the grass, and even down the street! A totally confined area can however benefit from their presence. If the problem is a walkway where the grass won’t grow, try flagstones, and then plant things like, creeping thymes, wooly yarrow, or mosses between the stones. These are attractive, require little attention once established, and can take a little walking on. No plant will take regular heavy traffic.
Plants that are good for, dry, sunny areas are: New Zealand bur (Acaena species) try microphylla, it grows to 4"(10cm) will do well under shrubs, and is hardy to zone 3.
Daylilies (Hemerocallis) – great for covering large swathes of soil. Their green, swordlike leaves look good all through the season, and their flowers are lovely. If you take the time to purchase late spring, summer and fall flowering plants, there will be a display all season. There are many re blooming ones now too.
Knotweed (Polygonum) – try P. affine (fleeceflower,) or P.bistorta which is a little taller. Both have pink to reddish flowers in summer. Keep away from P. cuspidatum as it is too invasive.
Think about Hens and chicks (Sempervivum) there are so many now, and they look so good in open sunny spots. Speedwell (Veronica)- try V. incana, V. prostrata, or V. repens these have nice foliage, do better in less fertile areas where they won’t become so leggy. Of course we can’t forget all the creeping and low-growing thymes.
Shaded areas have their helpers too. Sweet woodruff (Galium odoratum is very happy in deep shade and takes some drought conditions. They produce white star shaped flowers in spring. Even grows under evergreens like white cedar.
Lady’s Mantle (Alchemilla mollis) loves deep rich soil, but can tolerate some dryness with occasional watering.
Solomon’s seal likes moist shaded areas but can tolerate some drought and sun, and will not wilt as some other plants do. They have bell-like flowers that hang down from their 2-foot stems in spring.
Cranesbill Geranium- For best ground cover use ‘macrorrhizum’. These have fragrant foliage, pink flowers in spring and off and on throughout the summer. Cut back, to reduce self-seeding. They will tolerate some sun.
Sunny, good fertile soil areas will look terrific with a cover of Carpet roses. Try "Snow Carpet" or "Nearly Wild" which grows to about 3’ with pink flowers, or "Ralph’s Creeper" which is 18"(45cm) and has red flowers. They would look lovely tumbling down a slope.
Cotoneaster- shrubby but a good cover and it is evergreen. Prefers alkaline soil. They can be propagated by layering as each branch roots easily.
Ground covers can be the answer to many gardening problems. Remember to investigate the growing habits of the plants you choose so that you don’t create more problems than you already have. Nothing is completely care free, but groundcovers can certainly improve the landscape, cut down on erosion, reduce the need for watering, and cut down on the growth of weeds. Start in a small area, and get a feel for these helpful plants then let your imagination fly.