Delaware Gardener in the News Journal: PLANTING GROUNDCOVER IN LANDSCAPE BEDS
Sustainable landscaping depends upon learning from natural systems and trying to recreate the elements that make them successful in the planned and planted landscape. So, let’s look at a natural woodland or forest. It usually has a canopy layer comprised of tall trees like tulip poplar, sycamore, oak, hickory and maple. Then there is an understory tree layer. This may contain beech, ironwood, dogwood, redbud, and birch, to name a few. Next, the shrub layer in our woods is comprised almost entirely of spicebush because our rampant population of white tail deer has eaten everything else, but it should contain other native shrubs like viburnum, witch hazel, winterberry holly and deciduous azalea. That takes us to the ground layer – also primarily eaten by deer in our natural woodland—but important in a functioning forest. The ground layer reduces erosion, helps water infiltrate and provides competition for invading plants.
So, let’s focus on that ground layer, which is often forgotten in the planned landscape. People seem to have almost as strong a love affair with mulch as they have with mowed lawn. The ultimate goal of a planted landscape should not be to have individual shrubs that are surrounded by brown mulch! That’s not sustainable because mulch must be reapplied every year and it doesn’t look natural. Instead, the goal should be to have a solid mass of ground covering plants as the ground layer with shrubs and trees coming out of that mass. This may take a little while to establish and mulch is a good temporary solution to reduce erosion, increase infiltration and reduce weeds. But, plan to have your plants take over this responsibility ultimately.
When planning your ground cover, think about using large masses of relatively few types of plants. Too many different plants will appear confusing and detract from your trees and shrubs. Decide where ground cover is needed. Some shrubs are low to the ground and do not need ground cover plants below them, but others are higher branched and would look great with a uniform ground cover underneath.
Here are a few good ground cover plants. Allegheny pachysandra is our native pachysandra and while it takes a little while to become established, looks great once it gets going. There are many great native and non-native ferns the deer don’t eat them. Yellowroot is another native groundcover that grows well in wet soils but also tolerates dry conditions. It has somewhat inconspicuous purple spring flowers but turn yellow in the fall. Wood aster is a great ground cover for both shady and sunny locations. There are many sedges (again some native and some non-native) that can form a nice carpet in the landscape. Barrenwort is not native but is one of the best ground covers for dry shade. Plumbago is another non-native that grows well and has blue late-summer flowers and burgundy fall color.
Ceratastigma plumbaginoides (plumbago) as a ground cover at the Delaware Center for Horticulture (photo by Gary Schwetz).
Carex ‘Blue Zinger’ starting to fill in this landscape bed as a ground cover beneath the sweet bay magnolia.