How To Garden On A Slope

Should I use a single type of plant to create a carpet? Or is a mix of different plants better?

It is not a good idea to use just one type of plant on a slope. Trying to create a uniform look tends to highlight the flaws, such as a dead plant or weeds. Filling a hillside with a mixture of plant types – trees, shrubs, perennials and ground covers – forms an eye-catching garden that also helps diffuse the impact of rain on the slope.

For a low-height garden option, plant a mix of groundcovers for slopes that flower at different times of the year. Allow plants to battle for real estate as they grow, and you will wind up with flourishing plants that are best suited to your growing conditions.

What types of plants work well on slopes?

Some of the best plants for a slope are ground covers that tend to root along the length of their stems, forming a mat. Clumping plants, which produce several stems from one root, also work well. Deep-rooted plants, such as prairie plants, hold their own on even the steepest slope. Ornamental grasses, ground cover roses and shrubs (including shrub roses with a sprawling growth habit) work well in hillside and slope planting. Native plants are nearly always an excellent choice.

Can I plant wildflowers on a slope?

Drifts of wildflowers dress a slope with multi-season interest and are easy to maintain. For wildflowers to naturalize and create a self-sowing garden, you will need to mow or cut stems down after plants go to seed (after a hard freeze in cold regions). For the first year or two, until plants establish, weeding is vital. In other words, wildflowers work best when a slope isn't so steep it prevents easy access. When sowing wildflowers from seed, spend the money for a top-quality seed mix, which will have fewer weed seeds.

Are there no-mow grasses I can plant on a slope?

Check with your local Cooperative Extension System office to learn if any varieties of Buffalo Grass will survive in your region. Also ask if there are any types of Fine-Leaf Fescue for your region that can be grown without mowing.

If a slope is not steep, can I grow turf that needs regular mowing?

Yes, you can. The general rule of thumb is to avoid mowing turf on slopes less than 10 feet wide and steeper than a 25% grade. The bigger challenge with growing grass on a slope is watering. This is a vital consideration in areas with dry summers. Any water you apply tends to run downhill, so you can end up wasting a lot of water.

Are there any plants I should avoid?

Many plants typically suggested for a slope have tenacious growing habits and can easily become invasive. Check with your local Cooperative Extension System office or garden center before planting to ensure that your plant choice is not a potentially scary one.

These plants can prove problematic due to their invasive potential: Crown Vetch, Japanese Barberry, Scotch Broom and Virginia Creeper. Plants such as English Ivy, Liriope, Vinca and Ajuga work very well on slopes but can invade nearby lawns. Contain these plants using barrier edging. Snip stray Ivy or Vinca stems.

Also avoid planting shallow rooted trees on a slope. The risk of toppling is too great.

Are there any other issues to consider when planting a slope?

How to Plant on a Steep Slope: Steep slopes are serious business. Before planting them, check with a local landscape contractor to ensure you are not creating a potential erosion problem that could endanger your home.

What are some great plants for a slope?

For Sun

  • California Lilac (Ceanothus spp.)
  • Catmint (Nepeta spp.)
  • Creeping Juniper (Juniperus horizontalis)
  • Forsythia (Forsythia — try "Arnold Dwarf" for small spaces)
  • Little Bluestem Grass (Schizachyrium scoparium)
  • Prairie Dropseed (Sporobolus heterolepis)
  • Purple Coneflower (Echinacea purpurea)
  • Rattlesnake Master (Eryngium yuccifolium)
  • Rockrose (Cistus spp.)_
  • Rockspray cotoneaster (Cotoneaster horizontalis)
  • Rosemary (Rosmarinus officinalis)
  • Russian Sage (Perovskia atriplicifolia)
  • Shrubby Cinquefoil (Potentilla fruticosa)
  • Snowberry (Symphoricarpos spp.)
  • Star Jasmine (Trachelospermum spp.)

For Shade

  • Astilbe (Astilbe spp.)
  • Common Periwinkle (Vinca minor)
  • Japanese Pachysandra (Pachysandra terminalis)
  • Lily-Of-The-Valley (Convallaria majalis; leaves turn yellow in summer; plant with a partner that looks good in summer)
  • Siberian Carpet Cypress (Microbiota decussata)