Hillside Planting in Oregon

Soil Testing

• Frequently, says Bonner County Master Gardeners, hillside soil is depleted of nutrients. Rain washes away the best soil, leaving hard, dry earth behind. Therefore, begin by testing your hillside soil in several locations. Make a record of the results, and take it with you to a nursery. If you're unsure whether a plant will grow or thrive in your soil, ask a nursery specialist.

Plant Selection

• Which plants you choose depend not only on your USDA gardening zone and your soil test results, but also on the very fact that you're planting a hillside. According to Las Pilitas Nursery, which specializes in gardening for erosion control, almost any hillside can be made stable with the right plants. For best results, the hillside should feature a mixture of groundcovers, perennials, bushes and trees. Annuals, the nursery says, should be avoided, as should perennials that need division every year or two. The idea is to disturb the soil as little as possible.

  Some good choices for hillside planting in Oregon include Franciscana manzanita, Carmel creeper (Ceanothus griseus horizontalis), St. John's wort (Hypericum), salvia, dwarf coastal manzanita (Arctostaphylos edmundsii), golden globe arborvitae, coyote bush (Baccharis pilularis pilularis), juniper, California grape (Vitis californica) and bearberry cotoneaster (Cotoneaster dammeri "lowfast").

Mulch

• Any small areas not planted should be covered with about 3 or 4 inches of mulch. This will tame weeds and help prevent water runoff. For best results, choose a coarse mulch, like shredded bark. Avoid chunky mulches, like bark nuggets, which will wash down the hill in the first good rain.

Pathways

• To prevent disturbing the hillside soil as much as possible, create pathways for tending the garden. If the hillside is particularly steep, build steps. A wood edging or low brick wall may be necessary along the sides of the pathway, but avoid gravel or other loose coverings that could cause someone to slip.

Design

• Terraced designs are popular for hillsides, but it's smart to hire a landscaping expert to design one for you. It's not enough to just dig into the soil and bury some railroad ties. To prevent further erosion, you'll want to dig in the soil as little as possible.

  When it comes to the layout of plants, study nature for ideas. Intersperse trees and taller plants, and keep most---but not all--of them near the top of the hill. Use plenty of groundcovers. Avoid grass, since it may actually aggravate erosion problems, according to Las Pilitas Nursery.