Fall is the Best time of the Year to Plant Trees, Shrubs and Perennials

Fall is good time to plant trees

Brian Jervis:  Ask a Master Gardener

Saturday, October 8, 2016 12:00 am

Q: Is it best to plant trees in the spring or fall? B.F., Tulsa

A: The question brings to mind the adage, “The best time to plant a tree was 20 years ago. The second best time is now.” — Chinese Proverb

The short answer is that fall is an excellent time to plant trees; but spring and fall are acceptable times of the year to install trees, shrubs and perennials. There are some exceptions, however, depending on the plant type.

An appeal of fall planting is that many gardeners are enthusiastic about returning to the garden following the heat of summer. In addition, one is likely to find some bargains in the nursery stock in fall.

The advantages of fall planting is that trees are entering dormancy and no longer expend energy on making new leaves. This means that most of the plant’s energy can be directed toward growing a root system, in preparation for next year’s growing season. The soil usually remains warm enough for roots to grow well into winter.

Due to high demands and a limited root system, plants installed in spring or during summer may experience water loss from leaves that exceeds the plant’s ability to deliver. In spring, all newly-planted trees need careful irrigation and mulching.

Fall planting gives trees a head start. OSU performed a study comparing a variety of 2-year-old trees that were planted in spring and fall. They found trees planted in fall had up to 50 percent larger root balls and trunk thickness when compared with spring-planted trees after one growing season. This advantage applies not only to trees, but also to shrubs and ornamentals.

However, most bare-root plants should not be planted in fall but in spring between mid-February and mid-April or up to the end of the frost period. They must grow tiny rootlets to absorb water, and this happens as buds begin to swell in spring. Other than seedling-sized evergreens, only deciduous plants can be transplanted with bare roots, and then only when dormant or leafless.

Another exception to fall planting are evergreen shrubs. These shrubs will continue to lose water in winter, and the demand may exceed the root’s ability to deliver. If they are planted in the fall, they must be watered frequently, sheltered from wind and have a thick layer of mulch.

An additional concern about fall planting relates to crape myrtles. Carl Whitcomb, a retired OSU professor and expert on crape myrtles, recommends they be planted in June through early September and not after October. They need warm soils to grow water-absorbing roots, and the cool soils of winter prevent the development of these roots.

For more information about tree planting, obtain the OSU fact sheet “Planting Trees and Shrubs” online. This fact sheet has the what, when and how to plant trees in all types of soil. Also see Whitcomb’s book, “Establishment and Maintenance of Landscape Plants,” for additional authoritative information.

Garden tips

§  Plant cool-season annuals like pansies, ornamental cabbage or kale, snapdragons and dusty miller when temperatures begin to cool.

§  Prune trees or shrubs anytime there are dead or diseased limbs. Do not perform routine pruning now. Pruning before winter dormancy may stimulate new growth sensitive to the cold. Fall pruning also removes energy stores needed for winter survival.

§  For summer-blooming shrubs, prune in late winter before spring growth starts, and prune spring-blooming plants, such as azaleas, after blooming is completed.

§  Continue to replant or establish cool-season lawns like fescue. Mow and neatly edge warm-season grasses before the first killing frost.