Keeping ground cover away from perennial garden plants varies in difficulty depending on the perennials and the type of ground cover. The effort will also differ depending on the growing conditions.
Choose Ground Cover Carefully
The best way to keep ground cover away from perennials is to choose the variety of ground cover and the variety of perennials very carefully.
Different types of ground cover grow more or less aggressively. If you have a bed that is filled with only one type of ground cover, an aggressive variety may be just what you need for a completely successful bed.
However, if you want to have healthy, thriving perennials between that ground cover, you will want to choose a ground cover that is less vigorous.
Another consideration is the amount of light the garden area receives. Some varieties of ground cover thrive in direct sunlight, while others struggle with light and prefer partial shade and dampness.
One of the varieties of ground cover noted for its vigorous growth is vinca, or vinca minor.
Commonly known as periwinkle, this species of ground cover is valued for its ability to grow in partial sunlight. However, in many places it is considered aggressive, weed-like, and invasive. If you are attempting a perennial garden with this ground cover, you will be asking for a great deal of work.
Other aggressive ground covers are White Nancy, Bishop’s weed, cypress spurge, crown vetch, and Pachysandra.
Cooperative Ground Cover
The cooperative types of ground cover are less aggressive and grow more sedately. They are often easy to pull up if they begin to spread beyond the edges you have prescribed for them.
Some of the types to consider are slow-moving sedum, Georgia blue, waterperry, or lamium.
Keep It Trim
Once you have a slow-growing, noninvasive ground cover planted, you’lll need to monitor it carefully. Each spring, cut the plant back until it is within the location that you want it to be.
Don't relax your efforts in keeping the ground cover away from the perennials, even if you do not think it’s going too far out of the acceptable lines. It can go out of control in a hurry.
If the ground cover is invading the space of your perennials more rapidly than you’d like, be sure to pull it out by the roots, and not just clip back branches or blossoms. Ground cover roots are valued because they spread easily and get established quickly. However, too much of a good thing is a bad thing, and too many thick roots will choke out a perennial.
It can be very tempting to plant ground cover at the same time as you put in a perennial bed. Ground cover eliminates the need for weeding, and creates a great look for a flower bed. But it's much better for your garden to let the perennials become established before you introduce a ground cover and let it take root.