Question:
Is late summer/early fall a good time to plant trees?Answer:
Mid-August through September is an excellent time to plant pine, spruce, and other evergreens. (Evergreens planted in late October or November may not have adequate time to become established before the onset of winter and could be subject to desiccation injury and death.) Deciduous trees and shrubs can be planted from August through early November.
Water newly planted trees every day for 3 or 4 days and then gradually reduce the frequency of watering. When watering, slowly apply water to the rootball and the surrounding soil. A thorough watering every 7 to 10 days (in dry weather) should be sufficient 3 to 4 weeks after planting. Continue watering until the ground freezes.
More detailed information on planting trees can be found in this article: Tree Planting Basics