Landscaping a Hill With Perennials

The Terraced Slope

• Since the hanging gardens of Babylon, gardeners have terraced hills for easy maintenance. Large steps, dug into hillsides and held in place by stone walls or stacked wooden posts, make mini-gardens. Each terrace slopes gently downward to allow water to drain easily rather than puddle on the terrace. Steps divide terrace levels and allow access to plants. Terraced slopes landscaped with a different perennial or group on each level resemble a garden, sliced and given an added dimension by the stone or wood retention walls at each level. Less formal terracing resembles a stony hillside where groups of fieldstones hold soil for planting. English ivy, crown vetch and vinca may be planted with spring bulbs but often need controls to keep them from becoming invasive.

Xeriscaping a Hill

• Mowing is difficult if the hill's slope exceeds 15 degrees, and grass does not grow fast enough to have the thick or deep roots necessary for the plant's survival and erosion control. Xeriscaping uses plants that absorb rainwater instead of letting it run off. Ground covers such as juniper and plumbago spread thick, thirsty roots that soak up precipitation. Yarrow, poppies, day lilies, sages and creeping phlox spread quickly, establishing strong, thirsty roots. Annuals such as cosmos and bachelor buttons reseed themselves.

Native Plants

• A major consideration in landscaping many slopes, especially those with large areas, is ease of maintenance. Access need not be only by stairs and terracing; gentle slopes invite grassy or mulch walks that meander through plantings. Native plants need less water and fertilizer because they have adapted to the local environment over hundreds and sometimes thousands of years. Purple coneflowers and black-eyed Susans do not need deadheading, and their seed heads provide winter interest. Columbines and wild indigo have deep roots and thrive in full sun.

Considerations

• Plans for landscaping a hill may include ornamental or fruit trees. Small terraces might contain vegetable patches. Perennials like asters, gaillardia and bergamot make an impressive display when planted on a slope, but gardeners should examine the slope carefully for microclimates. A slope facing south may have much warmer and dryer conditions than a north-facing slope. Azaleas may attract birds and butterflies on the sunny south-facing slope, but bright yellow coreopsis will attract wildlife with only partial sun on other slopes. One slope may have several microclimates, determined by the shade of trees and rock or timber walls.