Tips for Fall Pruning - Hint: DON'T DO IT!!
There's something about this time of the year that makes people eager to start pruning. With fall garden cleanup in full swing, maybe it's all the raking and mulching that makes people think to get a jump on Spring. But, the general rule on Fall pruning is DON’T DO IT! That's right, put your pruning shears back in the shed for at least a month or so - from Thanksgiving to the New Year.
Why Fall Is the Worst Time for Pruning
Pruning plants now stimulates new growth just when the plants are trying to go dormant, which severely weakens the plants. Plus, if you prune on a warm day, sap rises up into the plant. Then, it drops below freezing that night, and boom — not a pretty sight.
Instead, prune in the dead of Winter or in early Spring. Spring blooming plants can get a haircut right after they finish flowering but few plants other than fruit trees actually require it, and most gardeners do too much, not too little.
Still, proper pruning of overgrown flowering shrubs or fruit trees near your house will help the plants produce more flowers and fruit, which can also benefit wildlife. Doing it wisely can also help trees and shrubs give diseases and pests the cold shoulder. Just remember … don't do it in the Fall!
Waiting until Winter means that most woody plants are dormant, and because leaves have already fallen, it makes it easier for you to see what you're doing.
For early Spring blooming plants (like lilacs and spireas) that only need light pruning, prune them just after they finish blooming. For very overgrown deciduous shrubs, Winter pruning is probably best.
Never Prune When It's Wet
As a general rule of thumb, don't prune when it's damp outside -it spreads a lot of diseases. Damp weather encourages the growth of microbes that will make the most of the damage your pruning does. Wait until the sun's out for a little while; it dries out and kills mold and bacteria.
Know How to Prune
Pruning can allow more sunlight and air to filter through the trees and shrubs, which can help keep them healthy. When it's time to prune, focus first on removing dead or dying branches. If you see a sickly branch, cut between the diseased spot and the body of the plant. Prune branches that rub or cross each other (cut the smaller branch off), or if a branch is growing vertically. You can also take off really low branches that could interfere with foot traffic or lawnmowers.
Cut the branch as close to the source as you can - if you leave a stub sticking out, it's an area for bacteria and insects to harbor. And make sure you cut at the same angle as the branch collar — the furrow of bark where branch and trunk meet. If you’ve done it right, a circle of healthy callus will eventually swell around the spot.
Know What to Prune
There is a long list of trees and shrubs that you can prune from Winter until the sap starts flowing again in Spring. Some of them include: glossy abelia, beauty berries, hydrangeas, Bradford and Callery pears, crabapples, poplar, spruce, junipers, sumacs, cherries, and plums. However, because some trees can ooze sap when pruned in the Winter, you're better off waiting until the Summer to prune maples, birches, dogwoods, walnuts, and elm trees.
-Shrub roses—It’s best to tackle rose pruning in Winter or early Spring when plants are dormant. Wait to prune until after several hard freezes, or you risk triggering new growth.
- Perennials with disease issues—This list includes bearded iris, hollyhocks and any plants with a powdery mildew problem, like peony, bee balm and garden phlox. Cut stems back to 2 to 4 inches and destroy (don’t compost) the prunings.
- Suckers—Some plants send up shoots at and/or around the base of the original plant. With suckering shrubs, one plant can eventually form a colony. Examples include sumac, kerria, saucer magnolia, witch hazel and the colored twig dogwoods. Remove suckers whenever you spot them, cutting them as close to the base as possible.
- Plants prone to slugs—Slugs lay eggs in fall, so once a few frosts knock back plants, cut stems and leaves of hosta, delphinium, lupine and any other plant slugs attacked in force. Do not compost prunings; destroy them.
- Natural holiday décor—Feel free to prune a few branches from evergreens, berried twigs and even rose stems with hips to supply outdoor holiday decorations. Place pruning cuts carefully, remembering that you’re influencing future growth.
What Not to Prune
- Spring flowering shrubs and trees (things like azalea, lilac, dogwood, loropetalum, viburnum, oakleaf hydrangea)
- Ornamental grasses
- Marginally hardy perennials (plants you’re never quite sure are coming back until you see new growth in spring)
- Climbing roses
- Perennials that provide winter interest (tall sedum, baptisia, Siberian iris)
- Perennials with seedheads that feed birds (coneflower, black-eyed Susan, anise hyssop, tall liatris)
Breaking the Rules
Last but not least, you can always break the pruning rules if you don’t mind the consequences, such as not having flowers for one year or risking more severe winter kill on stems. For instance, a spreading shrub-like forsythia that’s gobbling ground is always a good target for pruning whenever you find the time. You can take down a summer bloomer like butterfly bush (Buddleja) in early winter, but in the coldest regions, you might risk losing the plant entirely to winterkill if winter is exceptionally hard. In this case, prune stems back to 24 inches, and shorten further in spring once new growth appears.
- JoEllen Urasky