Fall Pruning: Don't Do It!

As the trees go bare, you might be tempted to start hacking off some limbs, but fall pruning could cause more harm than good.

November 2, 2009

Drop those shears! Pruning should wait until mid-winter.

RODALE NEWS, EMMAUS, PA—There's something about this time of the year that makes people crave pruning more than vampires yearn for blood. With fall garden cleanup in full swing, maybe it's all the raking and mulching that has people going bananas. But before you start hacking at your trees and bushes, take a tip from a seasoned gardening expert. "The rules of fall pruning are simple: Prune nothing in the fall! That’s N-O-T-H-I-N-G! Nada! Bupkiss! Zilch! Zero! Ladies—hide the pruners from 'helpful husbands!'" pleads emphatic gardening expert Mike McGrath, author of Mike McGrath's Book of Compost, and radio host of WYYY FM Philadelphia's You Bet Your Garden radio show. That goes for shrubs and plants as well as trees, McGrath insists. "Hang little signs on your roses that say, 'Leave me alone until midwinter; or even better, spring.' There are no exceptions! Do not prune anything now. Got it?"

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Do you feel like you just got scolded by a third-grade teacher? Let it serve as a reminder that fall is not the right time to trim trees and shrubs, even though the fallen leaves have exposed all their imperfections. That's right, put your pruning shears back in the shed for at least a month or so.

Here are some pruning basics, to be used when it's a safer time to trim back trees and shrubs:

• Understand why fall is not prime time for pruning. "As I try to stress every year at this time, pruning them now stimulates new growth just when the plants are trying to go dormant, and this severely weakens the plants," says McGrath. "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, he suggests. That's if you can't stop yourself. "Spring bloomers can get a haircut right after they finish flowering. But get over this pruning obsession—few plants other than fruit trees actually require it, and most gardeners do too much, not too little," McGrath contends.

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 bloomers (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.

• Don't prune when it's wet. As a general rule of thumb, don't prune when it's damp outside. "Absolutely, do not prune if it's wet out, it spreads a lot of diseases," explains horticulturist April Johnson, landscape coordinator at the Rodale Institute. 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," she says.

• Know how to hack. 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. Johnson also recommends pruning when branches 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. "I prefer to prune back to the main stem. If you leave a stub sticking out, it's an area for bacteria and insects to harbor," says Johnson. 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 hack. According to Organic Gardening magazine, 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 Callory 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.

• Keep tools clean. Johnson says she prefers Felco Classic Manual Hand Pruner #F-2, and also uses hand-folding saws. No matter what type of pruning tools you decide to use, make sure you keep them clean. If you've cut out diseased branches, make sure you clean the tools thoroughly before moving on to another tree, to avoid spreading disease. Johnson says you can disinfect the tools by using just a teaspoon or two of bleach in warm water. Hot, soapy water also kills most germs. Remember to dry tools well after washing, too. And if you can't trim from the ground using pole pruners, or if there's any pruning to be done near power lines, make sure you hire a professional instead of climbing high and taking on the dangerous task yourself.

• Do your homework. We offer general pruning guidelines, but for more specific information on the trees and shrubs growing in your backyard, tap the brains of master gardeners involved with your local extension service, peruse OrganicGardening.com for free info, or buy Rodale's Illustrated Encyclopedia of Gardening and Landscaping Techniques, or borrow it from your local library.