Autumn is a great time to plant new trees and shrubs as well, but plant early to ensure proper growth. Amy Koldon, sales associate from Monrovia Nurseries, believes that planting in the fall gives trees a chance to start rooting in and get a jump-start on spring. "To ensure success with fall-planted plants, it is wise to keep watering until the plant goes completely dormant," says Kolden. "Plants that are full of moisture can hold up much better in the wi