Choose the right plants
In shady sites, large sweeps of creeping pachysandra (foreground) and clumping hostas (midground) placed together result in a lovely symbiotic planting.
Photo/Illustration: Jennifer Benner
While most of us have heard the gardening adage “right plant, right place,” I like to take this idea a step further. Although I’m careful to select plants that are suited to the conditions of my site, I also factor in the growth habits and growth rates of the plants I am considering. This is especially important if you plan to use more than one kind of plant in your massing or if your ground-cover area is adjacent to mixed beds or borders. The aim is a peaceful coexistence among the plants in your garden community. In other words, by placing rambunctious runners next to staid growers, you will be creating a gardening nightmare.
A good ground cover requires minimal maintenance to look its best and can be characterized as either a clumping spreader or a carpeter. Clumping spreaders, like Hosta cultivars, increase in size as they send out their outward-arching leaves each spring. Good clumpers rarely need division. Carpeters (or creepers), like spotted deadnettles (Lamium maculatum and cvs.) and Allegheny spurge (Pachysandra procumbens), spread by underground stems (rhizomes) or move across the soil surface, rooting at points where leaf nodes touch the ground. The best rhizomatous carpeters never require division unless they wander outside of their boundaries. Ideal surface-rooting carpeters only need occasional division to keep them vigorous.
Clumpers tend to be more polite, while carpeters generally cover an area fairly quickly. Clumpers and carpeters can coexist together, but you should do your homework on their growth rates. Plant references can be helpful, but I often observe amicable combinations in garden settings. Observation is also helpful when deciding which plants are visually appealing together. Using too many disparate heights and textures can look chaotic, while using too few can lead to a mass of nondescript green.