There is a false perception in the gardening world that autumn is the end of the growing season. In fact, it is quite the contrary. Autumn is an ideal season for planting trees and plants. The key is encouraging good root growth. Planting trees and shrubs in autumn enables the root systems to grow before the hot summer returns.The soil stays warm well after the air temperature cools and this encourages root growth.
April to June is the ideal time for tree planting because it allows the roots to become established before the ground cools and winter sets in. Stable cool air temperatures also promote rapid root development. Always protect the newly planted trees with a thick layer of mulch. This can be leaves, compost, bark chips or stones.