Sloping areas are usually dry so you must select plants which will tolerate periodic drought. Large, vigorous plants such as junipers or cotoneasters usually are grown on slopes. Use a fertilizer on the planting site when you prepare the soil. Spade the fertilizer into the soil. Follow recommendations for fertilizer for your area.
Fertilizer needs vary according to soil types and area of the country.
Although you can plant ground covers anytime during the growing season, early spring is the best time in most places. This allows the plants to become well established during a long growing period before winter. When you plant ground covers, space the plants so they will cover the site as quickly as possible, You may put small plants like bugleweed as close as 4 to 6 inches apart. Set such large plants as juniper or cotoneaster as much as 4 feet apart. Closer planting will cover the ground more rapidly but the cost of additional plants may be prohibitive.