How to Garden on a Slope: The Best Plants and Tips to Beautify a Hilly Yard

Tracy Heuermann transformed the steep grade of her Illinois backyard into a cascading garden. Here's how she did it — and how you can use her ideas in your own not-so-flat yard.

When Tracy first visited her future home on a one-acre site north of Peoria, she saw a treacherous hillside eroded into deep ruts. Water and gravity had steadily conspired to carry away topsoil and nutrients. Railroad ties barely held the hillside in place. It all got Tracy's imagination churning — enough to buy the place. A longtime Master Gardener and co-founder of the Midwest Hosta Society, she could see the potential: flowers grown on inclines, ascending like clouds of texture and color to embellish the slope.

Tracy and her contractor husband, Victor, visited the inspiring hillside gardens of England's famed Chelsea Flower Show. "The terracing on the cliff overlook at Kiftsgate made me believe that we could do this in our backyard," Tracy says. The couple carved five levels from their yard's heavy, clay-based soil and poured 12-foot concrete retaining walls to brace the tiers. About half of the height of each wall plunges below the surface of the hillside, anchoring it to the land. To soften the look of the man-made walls and transition the garden into the surrounding woodland, Tracy incorporated free-flowing, organic design elements, such as curvy grass paths and tumbling phlox.

Related: Shade Landscaping Ideas for Midwest Gardens

Today, Tracy and her husband have a beautiful hillside garden overlooking the emerald panorama of the Illinois River Valley. Tracy and Victor continue to develop the garden, nurturing new specimens and caring for established ones. "It's essential that the garden bring joy to you," Tracy says. "This one's brought a lot of joy to my family."

Here are Tracy's expert tips on how to fight soil erosion and which plants to choose for a slope.

Using these savvy tactics, Tracy turned eroded land into a fertile hillside.

Any plant helps, but those with deep, clumping roots (trees, shrubs, grasses) are especially effective, as are groundcovers, which find and fill empty spaces.

Related: 15 Easy Midwest Groundcovers

Pulling them disturbs fragile soil. Healthy plantings and groundcovers will eventually crowd out most weeds. Until then, use mulch to smother weeds and to fortify the soil. Pull weeds when they're small. Knock dirt from roots and put it back in the ground.

Place stones or boulders among plants to trap soil and moisture and slow water runoff. You'll get a more natural look by scattering rocks of a uniform type.

Related: Transform Your Yard into a Mini Mountainscape with a Rock Garden

It's a costly solution, and you probably need a landscape contractor for help. But terraces, softened by cascading plants such as creeping phlox, dramatically transform even the toughest terrain.

What are the best plants for a slope? Here are some of Tracy Heuermann's best bets plus picks from The Best Plants for 30 Tough Sites, compiled by University of Minnesota Extension Master Gardeners.