Growing Ground Covers
From the desk of....
Martha Maletta, Horticultural Consultant

Early fall is a good time to plant ground covers, those low growing plants that we use as complements to landscape plantings, alternatives to lawn and cover for difficult sites. One characteristic of good ground covers is that, once established, they are relatively low maintenance and problem-free.

This does not mean, however, that they don't require care to become established. All the same considerations for starting other plantings - trees and shrubs, lawn, vegetables, flowers - apply to ground covers. Plant selection for the site, soil preparation, irrigation, weed control are essential to success.

Plant choice depends on the site conditions and the purpose of the planting. Primary selection criteria include: light - full sun, light shade, deep shade; typical soil moisture conditions - wet, dry or normal; and soil drainage - poor, slow, good. Then consider function and site location and size. Are ornamental characteristics important, or is the ground cover to be strictly utilitarian, controlling soil erosion, for example. A plant like lily turf (Lirope spp.) is great during summer and fall but is generally not attractive during winter and early spring. Does it matter if the ground cover is evergreen or not or if the plant is fast spreading, even invasive?

Preparation for planting should include soil testing so that the right amount of lime and fertilizer can be applied and mixed with the top six inches of soil after existing vegetation - especially perennial weeds - have been eliminated. Most ground covers prefer only slightly acid soil which means liming may be needed. Fertilizer is very important in plant establishment and should, ideally, be applied according to soil tests.

If planting is at hand but no test has been done, use a fertilizer with a 2-1-1 ratio of N-P-K at a rate to supply 1 1/2 to 2 lb. actual N per 1000 square feet, e.g., 15 to 20 pounds of 10-6-4 fertilizer. Be sure to test soil next spring. It is also a very good idea to add organic matter (1 - 1 1/2 cubic yards per 1000 square feet) during soil preparation.

Mulching after planting is essential for controlling weeds, conserving soil moisture, preventing winter heaving and promoting spread of plants that increase by runners or stolons. Wood or bark mulch or salt hay are good choices because they will persist during the time it takes for the ground cover to establish. Regular irrigation will be important, too.

Some sites where ground covers are particularly useful can be difficult or tricky to plant and establish. Under mature trees, soil preparation and keeping up adequate irrigation are likely to be a real challenge. On slopes, stabilizing soil during establishment is critical. Working the soil and planting in 12 to 24 inch strips across the slope can help as can netting to hold mulch.

Most ground covers take at least two years to fill an area. During this time they will be relatively high maintenance plants requiring irrigation and weed control. Ultimately, the trouble taken to get a ground cover well established will be rewarded because most required little additional care outside of occasional fertilizer and lime.

Some of the best ground covers for our area are:
English ivy, pachysandra, myrtle (periwinkle), various low growing junipers, cotoneasters, gingers, sweet woodruff, hosta, certain sedums, mother of thyme.