Wait a little longer before pruning most plants

We’ve had a few frosts in eastern North Carolina and fall is definitely here, but pruning some plants now could be harmful to them. We haven’t had a hard freeze yet and many plants could yet have a growth spurt.

I know folks are anxious to tidy up their yards, but plant like angel trumpet and lantana should be allowed to die down completely. Pruning them now could encourage a flush of growth and almost certain major winter injury. I’d place butterfly bush in that category too.

There are plenty of other jobs that can be done around the flower garden on these pretty fall days. Weeding is one. Edging is another.

I don’t like fall pruning anyway, but as a general rule it should be avoided especially if plants are marginally hardy. We are in Zone 8, so zone 7 and 8 plants should never be pruned until they are completely dormant and that means winter. Early spring is fine too.

This is also true for fruit trees. Sometimes fall pruning encourages them to bloom. That poses a problem for winter hardiness and spring fruit set. It can encourage disease organisms too. Even if trees are damaged from injury I’d wait until they were dormant before working on them.

Plants in active growth become less winter hardy. Plant sap contains fewer solids and those solutes are essential for what I call plant antifreeze. Pure water freezes at 32 F. However, if sugars, salts, and other molecules are dissolved in it the freezing point is lowered.

Actively growing cells contain lots of water. When they freeze, their cell membranes are perforated by expanding sharp ice. The cells will die. In animals we call that frostbite.

When plants go completely dormant this phenomenon is far less likely to occur. This makes fall the worst time to prune. Fall is also bad if you have spring flowering trees and shrubs. All you will do is cut next spring’s flowers off.

Azaleas, Rhododendrons, dogwoods and redbuds should never be pruned in the fall. Neither should forsythia, lilac, Loropetalum or deciduous magnolias. Encore azaleas, the re-blooming types, need very little pruning. They should be trimmed immediately after they flower in the spring.

Many annual plants are still alive. I have some scented geraniums that are leggy but still hanging on. Since they are annuals and need to be replanted in the spring anyway, go ahead and clean them out if they bother you. This goes for any of your summer annuals.

Most perennials will be better served if they aren’t disturbed until winter. Mum buds might start to swell if plants are pruned now. This is also true for verbena. Candy tuft should also not be pruned until spring.

Usually, by the first or second week in December many plants are totally dormant and winter has set in. This is not one of those years. The main thing is to inspect your plants and pay attention to the weather. Serious cold could hit us in the next two or three weeks. Local forecasts call for frigid weather for mid-week, but it’s short-lived. We need a steady dose of winter for a week or two. Then some of your plants might be in line for some trimming.



Ted Manzer teaches agriculture at Northeastern High School (tmanzer@ecpps.k12.nc.us).

About tedmanzer

I grew up in Old Town Maine and got a B.S. at the University of Maine in Plant Sciences/ minor in Botany. From there I moved to West Virginia and earned a M.S. in Agronomy at WVU. I also met my wife there. She grew up in rural WV as the daughter of tenant farmers who raised cattle and hogs. Their lifestyle at times was one of subsistence and I learned a lot from them. I've always been a foraging buff, but combining my formal botanical knowledge with their practical 'Foxfire-type' background opened up my eyes a little more. I recently retired from teaching high school agriculture after 25 years teaching with my wife. Until recently I wrote a weekly nature/foraging column for the local paper (dailyadvance.com). I also have written several Christian nature/adventure novels that can be purchased on Amazon in Kindle format. One is a five book family saga I call the 'Forgotten Virtues' series. In the first book, Never Alone (presently out of print), a young boy comes of age after his father dies in a plane crash, and he has to make it alone. The second book, Strange Courage, takes Carl from his High School graduation to his recovery from a nasty divorce. The third book, Second Chances, takes Carl from his ex-wife's death and the custody of his son to his heroic death at age 59. The fourth book, Promises Kept, depicts how his grandchildren react and adjust to his death (this one is not yet published). In the final book, Grandfather's Way, his youngest and most timid granddaughter emerges from the shadow of her overachieving family and accomplishes more in four months than most do in a lifetime. I use many foraging references with a lot of the plants I profile in these articles in those books. I also wrote a romance novel titled Virginia. It is available on Amazon and is a different type of romance from a man's perspective.
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1 Response to Wait a little longer before pruning most plants

  1. tonytomeo says:

    For plants that get damaged by frost, I also recommend waiting until even later in winter to prune the damage away. Pruning stimulates new growth that is more sensitive to frost. Besides, the damaged parts insulate the growth below.

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