Fall is the best time to plant perennials, trees, and shrubs because they have time to acclimate to their new home before summer. Often we think of spring as the best time to plant, but that is not the case. Planting now gives your plants the longest possible time to get established before summer comes around.
Many think it is not a good time because the next season is winter, but this is when roots easily get established. When plants go dormant in winter, the energy is put into the roots, leaving months for them to build a healthy foundation. The plant is ready to focus its energy on new foliage and flowers when spring comes. Think about planting now as a head-start for your trees and shrubs.