Best Time to Plant Trees, Shrubs and More
by Don Janssen, Extension Educator
Landscape plants installed in March, April, and May benefit from generous rains and the long growing season that stretches ahead. But more often than not, we receive too much precipitation that makes planting difficult, especially on poorly drained sites. Furthermore, the sudden onset of hot, dry weather that typically displaces an often too-short spring, can injure tender new plantings. Because of these difficulties, increasing attention has been given to fall planting. During the period from mid-August to mid-October, moderate and relatively stable air temperatures prevail, and soil temperatures and moisture levels are usually in a range that promote rapid root development. But if the fall planting season is extended into November and December, or if slow-to-establish species are chosen, root growth may be poor and planting failures can occur.
Most container-grown and balled and burlapped deciduous trees and shrubs sold at garden centers are excellent candidates for fall planting. Because these plants usually possess well-developed root systems, and because the roots of many landscape plants are capable of growing even when soil temperatures cool to 45 degrees Fahrenheit, the prospects for successful plant establishment are quite high throughout the fall season. Conifers, such as pine and spruce, benefit from a slightly earlier start, preferring the warmer soil temperatures (60 to 70 degrees Fahrenheit) common in late summer to early fall (mid-August through September).
If plants from a nursery can be planted in the fall, what about moving or transplanting established trees and shrubs from one locale to another? Severing the roots of a plant (up to 95 percent in some cases), hauling it out of the ground, and moving it to a completely new site is a stressful operation, regardless of the season. Still, transplanting can be successfully carried out if it is restricted to those plants with a proven track record of surviving such a move in the fall.
Why can some plants be planted at almost any time of the year while others are saddled with much narrower windows of opportunity? Reasons for these differences are a subject for debate, but the commonly held belief is that plants with shallow, fibrous roots can usually be planted with greater ease than those with fewer, larger roots. Slow-to-establish species that are better planted in spring include fir, birch, American hornbeam, American yellowwood, ginkgo, sweetgum, hophornbeam, oak, willow, and bald cypress.
Notable tree species that can be successfully planted in the fall include maple, buckeye or horsechestnut, catalpa, hackberry, hawthorn, ash, honeylocust, Kentucky coffeetree, crabapple, Amur corktree, spruce, pine, sycamore, and linden. Most deciduous shrubs are easily planted in fall; however, broad-leaved evergreens like rhododendron and narrow-leaved evergreens like yew prefer to be planted in the spring.
Fall planting (mid-August to mid-October) takes advantage of favorable soil temperatures and moisture conditions that promote the root growth needed to sustain plants through their critical first year in the landscape. Unfortunately, our midwestern climate is unpredictable, and even the toughest plants may die if fall or early winter weather is severe or erratic. But if healthy, vigorous plants are chosen, if proper post-planting care is given, and if slow-to-establish species are avoided, fall planting of trees and shrubs can be as successful as spring planting.
University of Nebraska-Lincoln Extension in Lancaster County is your on-line yard and garden educational resource. The information on this Web site is valid for residents of southeastern Nebraska. It may or may not apply in your area. If you live outside southeastern Nebraska, visit your local Extension office