The best ground cover for slopes depends on how steep your hill is. Creeping phlox, prostrate juniper, and Pennsylvania sedge top the list for most yards. These three plants grip soil with strong root systems. They hold dirt in place during heavy rain and stop erosion before it carves gullies into your hillside.
I've planted slopes at grades ranging from gentle swells to steep banks that were hard to even stand on. The lesson I learned is that steeper hills above 30 degrees need plants with deep fibrous root systems that grab soil like anchors. Surface spreaders that run along the top look nice on flat ground but wash right off a steep slope during the first big storm. Choosing the right ground cover for erosion control starts with measuring how steep your hill runs and picking plants that match that grade.
Research backs this up. Duran Zuazo and Rodriguez Pleguezuelo found that plant cover cuts water runoff. It also boosts water soaking into the soil. Grasses with fibrous roots ranked among the most effective slope holders. Their dense root networks trap soil and slow water flow. This means ground cover for erosion control does more than look nice on your hill. It protects the structure of the slope itself from washing away over time.
The plants you choose should match your slope's steepness and sun exposure. Penn State Extension recommends River oats, Little bluestem, and Muhly grass for steep native slopes where deep roots matter most. Gentler slopes under 20 degrees do well with creeping phlox and sedum, which spread faster but root more thin. A medium-grade slope between 20 and 30 degrees works best with prostrate juniper or Pennsylvania sedge. Both offer decent spread speed and solid root depth.
Gentle Slopes Under 20 Degrees
- Creeping phlox covers ground fast and adds bright spring flowers in pink, white, and purple across your hillside.
- Sedum handles dry sunny banks with zero irrigation and stays low at 3 to 6 inches (8 to 15 centimeters) tall.
- Creeping thyme works on gentle slopes with full sun and adds the bonus of a pleasant scent when you brush past it.
Moderate Slopes 20 to 30 Degrees
- Prostrate juniper sends woody roots deep into hillside soil and stays evergreen through all four seasons.
- Pennsylvania sedge tolerates both sun and shade while its fibrous root mass holds soil tight on moderate grades.
- Daylilies offer dense root clumps and tall foliage that slows rainwater before it picks up speed down the hill.
Steep Slopes Above 30 Degrees
- Little bluestem drives deep roots into steep banks and survives drought once established without any watering help.
- River oats thrive on steep shaded slopes and spread through rhizomes that create a dense underground network.
- Muhly grass anchors steep sunny banks with fibrous roots and adds pink plume flowers in fall for visual interest.
How you plant on a slope matters just as much as what you plant. Set your hillside ground cover plants in staggered rows across the slope rather than in straight lines running downhill. Straight rows create channels that funnel water and speed up erosion. Staggered placement breaks up water flow and gives each plant room to spread without competing for the same strip of soil.
Apply 2 to 4 inches (5 to 10 centimeters) of mulch between your new hillside ground cover plants while they establish roots. This mulch layer holds the soil in place during rain storms and keeps moisture around the roots during dry spells. Use shredded bark rather than round nuggets that roll downhill. Within one to two growing seasons your plants will fill in enough to hold the slope on their own without the mulch doing all the work.
Read the full article: 10 Best Ground Cover Plants for Any Yard
