Q&A: Groundcovers for a Hill
Q: I have a steep yard that I don't want to mow. What's a good fast-growing, non-invasive groundcover for a mostly sunny area?
A: You have plenty of choices: Various junipers and other typical groundcovers are often selected for full-sun sites, but you can broaden the definition of groundcovers by also considering wide-spreading shrubs. The Prague vibrunum is a fast-growing shrub that offers white spring flowers and mostly evergreen leaves and eventually achieves a 10-foot girth. Snow-in-summer (Cerastium tomentosum) produces white flowers in summer and has fuzzy, gray-green leaves (USDA Zones 3 to 7). The Knockout rose would love a sunny area and give you lots of color too. And because it's self-cleaning, you wouldn't have to deadhead the blooms.
Junipers are slow-growing, so you might want to combine them with a fast-growing herbaceous plant like hardy geranium. 'Rozanne' blooms for a long period of time — all summer until first frost. And if your summers are sizzling, you might want to consider groundcovers that thrive in dry heat. And for still more options, try some vines that can grow out as well as up.
If you can't afford to plant the whole hillside at one time, carve out plantable landscape beds on the steepest part of the slope, and start with those. If the slope is very steep, be sure to secure the mulch with netting to keep it from washing away.