Anything that covers the ground is considered a ground cover. Covers can be close to the ground or not, can be shade or sun lovers, and can fill in garden gaps or be planted to take over large swatches. The only real qualification for a cover is that it must hide bare soil. An implied qualification expects ground covers to expand over an area. Gardeners themselves set other requirements, according to considerations such as environment, whether the cover should fix problem areas and whether a person wants to eliminate the need to mow grass.
Foamflower is a good choice if you have a woody area---and, likely, some bald spots where trees block light. The plant can enjoy different light conditions, from sun to dense shade, according to the University of Illinois Extension. It's a hardy perennial.
Foamflowers grow in mounds, reaching about a foot tall. Planted about 16 inches apart, individual plants grow together to cover the ground.
Foamflower leaves can be variegated. Meanwhile, the perennial produces white sprays of flower spikes in spring. Spikes can appear throughout summer.
If you're looking for an alternative ground cover to grass, it is likely because you can't or don't want to mow, you have a shady patch (or expanse) and/or your soil is acidic enough that changing it seems like too much of a battle. If one of these is your problem, moss might be your solution.
Mosses are evergreen plants that retain their color with less water than grass requires. Indeed, you don't have to water moss. (You don't have to fertilize it either.) The ability of moss to retain water means less water and snow-melt runoff, which, in turn, means less erosion.
Mosses don't take to traffic, though. You'll have to create paths where people will walk with materials such as pavers or stone. Think of raking as a form of traffic, and do it gently only if you have to.
The soil pH that mosses enjoy is around 5 to 5.5. Pure water possesses a neutral pH of 7, while the majority of plants grown by gardeners like a slightly acidic soil somewhere between 6 and 7. Gardeners with acid soil have to add lime to amend soil in order to grow these plants. With moss, it's not necessary.
It will take about two years for your moss lawn to become well-established, according to Rutgers University.
Sedum is a great ground cover alternative for soil that is rocky and poor in nutrients. Another plus is that sedum tolerates drought.
The varieties of sedum are many--some growing up to 3 inches high, others up to 2 feet tall. The different sedums also feature a lot of different textures and leaf colors. The leaves of sedum are succulent.
Flowers appear in early summer and these might bloom yellow or red, depending on the sedum type. Flowers usually means sun-loving, and sedum does enjoy full sun, though it can also handle a small bit of shade. Sedum thrives in well-drained soil.