Many times, the ideal time to begin planting trees and shrubs is six weeks before the first sign of hard frost. September through November is the ideal time for tree planting because it allows the roots to become established before the ground freezes and winter sets in.
Fall season planting (mid-August through mid-October) offers many advantages that may outweigh spring planting. Transpiration is low and root generation potential is high. The temperatures are typically moderate to cool and are easier on the plants so there is less chance for the trees to be stressed by extreme heat. The fall moisture (rains) helps the trees and shrubs establish their root systems. When the air temperatures are cooler than the soil, new root growth is encouraged without new top growth. The result is a stronger, better developed root system for the next spring when the plant begins to grow. Mulching with wood chips helps retain the soil’s required moisture.
If you wait too long into the fall season (November – December) to plant, you run the risk of poor root growth and increased failure rate. Conifers, in fact, need a slightly earlier start than hardwoods, preferring the warmer soil temperatures of the summer to early fall.