How to Plant on a Hill or Mountainside
- 1). Build a retaining wall system. Make a series of lower walls with terraces between them. The size of the walls and level areas is completely up to you. Terraces will limit runoff and erosion, and give you even planting surfaces. Use rocks, concrete, railroad ties or bricks to construct the retaining walls. For complex retaining wall systems, hire a landscape engineer.
- 2). Buy plants for the hill or mountainside that can live in the microclimates that often exist on slopes. Cold air sinks to the base of the hill, so delicate plants may not survive there. Choose plants that can live in the sunlight conditions, as well as those that are low maintenance. Weeding, pruning and deadheading are difficult tasks on hills and mountainsides.
- 3). Gather soil samples from various locations for a soil pH test. The results will tell you which amendments or organic matter you need. Add as specified.
- 4). Apply an herbicide to rid the area of weeds and dead grass. Removing them right before planting will help your plants thrive. Don't remove all plant life far in advance, because those plant roots are keeping the soil from eroding. Follow the label instructions.
- 5). Plant perennials for a lower maintenance slope. According to Garden Aesthetics, suitable trees include vine maple, staghorn sumac, willow oak, river birch, black willow and Oregon ash. Shrubs like Rosa macrantha, azalea, red osier dogwood, heather, salvia, viburnum, rock rose and rhododendron grow well on hills. Perennials such as hardy geraniums, climbing hydrangea, ivy, juniper species, ferns, rosemary and groundcover roses are also good choices.
- 6). Plant trees and larger shrubs "out-of-the-hill." Adjust the grade by adding soil to the slope in the planting location. Make a berm that extends out from the hill, creating a level planting spot. Dig a hole in the center and place the tree in it so that it grows vertically. This way, the tree's roots will be covered with soil instead of sticking out of the hill. Instead of an angled slope, the ground will "bump" out.
- 7). Stagger the planting holes. Straight rows will clog up water runoff. Make the holes large enough for root spread and development. Stake plants until they become established.
- 8). Spread organic mulch between the plants. Use 2 to 4 inches of shredded bark or leaves because it will decompose and improve the soil. Irrigate the plants with drip irrigation or soaker hoses. Aim for deep waterings near the roots, as opposed to overhead light waterings. This will improve erosion control.
- 9). Vary the plants so there are different root depths and plant heights. Using all shallow plants can cause problems. Deeper root masses will stabilize the hill or mountainside.
