Hilly ground can present gardening challenges. A slope may be the only available space for outdoor living. But if it's not planted or stabilized properly, it can present a hazard in wet weather.
Marta Krampitz's Oakland, California, garden is gorgeous and usable. For years the steep canyon garden played host to weeds. Krampitz needed a place for her three young boys to run, and she wanted a prettier setting in which to entertain. And her garden needed to be low-maintenance, require only modest amounts of water, and be able to withstand damage from deer.
Landscape designers Richard Sullivan and Shari Bashin-Sullivan came up with the perfect solution, transforming Krampitz's hillside into a colorful tapestry of long-blooming perennials and shrubs. These include Aster x frikartii, 'Sunset Gold' breath of heaven, Geranium incanum, Loropetalum chinense 'Plum Delight', and Santa Barbara daisy. "The hillside is like a picture," Bashin-Sullivan says of the texture and colors.
Build retaining walls to create terraces; connect the terraces with zigzag pathways. Before construction on steep slopes, it's a good idea to review your plans with a structural engineer.
Install jute erosion-control netting before planting on steep slopes. Unfurl the rolls on the slope across the grade; secure them to the ground with U-shaped galvanized or plastic-coated pins (usually sold with the jute). Cut small, X-shaped holes in the jute and plant the seedlings or plants through them.
Choose plants with dense, strong roots that help hold the soil. Examples: artemisia, ceanothus, cotoneaster, creeping mahonia (M. repens), ice plants, juniper, rockrose, rugosa roses.
Arrange plants in staggered rows when setting them on a slope where erosion may occur.
Install drip irrigation so plants get the amount of water they need without a lot of runoff. Place emitters uphill of the plants.
To catch rainwater, build berms on the downhill side of the plants using soil from the planting holes.