Posted on Oct 02, 2019 | by Kerry Kelley
Fall is here—a great time to get out in the garden again. Unfortunately, the cooler temperatures herald an onslaught of gardeners hacking away at every bush and tree, figuring it’s time to trim that hedge and shape those bushes. Well, I have one word for them—STOP!
Hate to break the bad news, but if the pruning hasn’t been done by now, chances are it will do more harm than good. Granted, most folks don’t know when to prune, so they do it when it’s most convenient. Of course, they’ll be the ones wondering why those azaleas aren’t blooming in the spring.
Fall pruning can be harmful for several reasons:
- Pruning stimulates new growth, which is stressful for a plant when it’s trying to achieve dormancy
- Pruning cuts don't heal as quickly in fall
- Late season new growth is soft and easily damaged by frost
- Diseases are more likely to be spread by pruning in fall rather than late winter
- Plants that bloom in early spring (most azaleas, many hydrangeas, lilacs, rhododendrons, camellias, for example) form their buds the previous year, so fall pruning removes them
Dead, diseased, or damaged parts may be pruned at any time—for the health of the plant, and possibly the safety of you and your home.
Best Time to Prune:
- Most deciduous shrubs and trees should be pruned in late winter or early spring, when in full dormancy. Visually, it is easier to prune deciduous types when the branch structure is not hidden by the leaves.
- Early spring bloomers should be pruned within a month or two of cessation of flowering
- Summer bloomers (roses, non-reblooming hydrangea varieties, crape myrtle, rose-of -sharon, butterfly bush) may be pruned in late winter or early spring before or just as new growth begins
- Non-flowering broadleaf evergreens (hollies, euonymous, boxwood, privet, etc.): early spring, and again early to mid-summer for more vigorous varieties.
- Conifers: The goal here should be to plant specimens that will not outgrow your space, as most are not tolerant of indiscriminate pruning. Special rules apply for various types:
- Arborvitae: Prune early spring or mid-summer. Usually tolerates heavy pruning if necessary, but complete before new growth begins so that new growth will cover cuts. Some older plants may develop a bald area in the center—do not prune back into old wood with no foliage as it will not regenerate.
- Junipers: Never prune back into wood with no foliage—it will not regenerate and you will be left with a naked stub. For a natural form, prune individual branches in early spring. For a more formal look, lightly shear in spring after start of new growth.
- Pines: Generally should not be pruned. New shoots (candles) grow only from terminal buds at ends of branches, once per year in spring. Candles may be pinched individually by 1/3 to ½ as they emerge to maintain shape. Do not prune back into previous year’s growth-no new growth will develop from cut ends. Overgrown branches may be entirely removed at the trunk.
- Spruce/Fir: Individual branches may be cut back to a lateral branch or visible dormant bud at any time. Shearing should be done in late spring ONLY on new growth after it has filled in.
- Yew/Hemlock: Prune for size before new growth begins and again in early summer if necessary. Shape by shearing after new growth is filled in and through August as necessary. Do not prune after August.