Is it Too Late or Too Soon to Prune?
Ask a Specialist: Do You Have Pointers on When to Prune?
Answer by: Taun Beddes, Utah State University Extension horticulturis
Now is the time to put the yard to bed for winter and rake leaves, shut down the sprinkling system and cut back perennials. Many gardeners also prune trees and shrubs, but now may not be the best time since many woody plants should not be pruned in the fall. This is especially true for shrubs. Instead, prune hedges and summer blooming bushes (rose of Sharon, butterfly bush, blue mist spirea and others) as the snow melts off in early spring. Hedges can be trimmed until late July to maintain their shape. Prune spring flowering shrubs (lilacs, snowball bush, spirea, viburnum, forsythia and others) within a week of when they quit blooming.
Below is a list of common landscape trees and when to prune them, primarily taken from the American Horticultural Society’s Pruning and Training book.
* Ash - Late autumn to midwinter when fully dormant.
* Crabapple - Autumn to early spring. Light pruning to remove water sprouts in the summer is acceptable.
* Elm - Autumn to early spring.
* Flowering pear - After leaf drop in autumn to early spring.
* Flowering plum - Midsummer.
* Fruit-producing pears and apples - February to early March before buds start to swell. Light pruning to remove water sprouts in the summer is acceptable.
* Hawthorne - Between autumn and early spring.
* Honey locust - From late summer to midwinter.
* Horse chestnut (buckeye) - After leaf drop in late autumn to midwinter.
* Japanese flowering cherries (kwanzan, akebono, etc.) - Immediately after flowering in the spring.
* Japanese zelkova - Late winter.
* Juniper and arbor vitae - Late spring to early summer. Trim when new growth is fully extended but not hardened. Do not remove more than one-third of the new growth. Remove any branches at a branch intersection.
* Magnolia - Early to mid-summer, after leaves are fully expanded.
* Maple - In the winter when fully dormant.
* Mountain ash - Autumn to early spring.
* Oak - Winter to early spring.
* Pine, spruce, true cedar (Cedrus spp.) and fir - Late spring or early summer. Trim when new growth (candles) are fully extended but not hardened. Do not remove more than one-third of the new growth. Remove any branches at a branch intersection.
* Poplar (cottonwood, aspen) - Late summer to early autumn. Be cautious since excessively pruning older trees may make them more susceptible to internal rot and canker diseases.
* Redbud - Early summer.
* Stone fruits (cherries, peaches, plums and apricots) - In March before buds start to swell but the coldest winter temperatures are past. Light pruning to remove water sprouts in the summer is acceptable.
* Sycamore - Autumn to early spring.
* Walnut - Midsummer to before midwinter.
* Willow - Autumn to early spring.
Direct column topics to Julene Reese, Utah State University Extension writer, Logan, Utah, 84322-4900, 435-797-0810, firstname.lastname@example.org.