The following are some planting basics for landscapers to consider.
Proper planting is the key to healthy plants that can resist drought, insects and diseases. A well-prepared planting bed, dug to a depth of 12-15 inches and enriched with organic matter, encourages strong root development for shrub masses, islands and flower borders.
• Dig the bed and remove rocks and clods. Add lime, if indicated by a soil test. Incorporate approximately 2 inches of of fine organic material such as compost. Peat moss by itself is not recommended because it is devoid of nutrients and is difficult to rewet once it dries. Thoroughly
mix the organic matter with the native soil.
•When planting individual trees and shrubs, omit the organic matter and break up the native soil in a wide area around the planting hole. The panting hole should be at least twice the diameter of the root ball.
• Loosen and spread apart root balls to encourage roots to grow outward and to allow water to penetrate into the root mass.
• Before planting, check sub-surface drainage by filling the hole with water and allowing it to drain. If water stays in the planting hole for more than an hour, drainage is poor and needs to be corrected before planting. A slope is no guarantee of good sub-surface drainage. Raised beds or drainage tile may need to be incorporated to improve the site.
Information from "Environmentally Friendly Landscape Practices" By Robert R. Westerfield, Extension Horticulturist and Daryl Pulis, Master Gardener Advanced Training Coordinator, University of Georgia http://pubs.caes.uga.edu/caespubs/pubs/PDF/C967.pdf