It’s downright chilly some mornings now that October is here. The sky is bluer and the humidity is lower. We take a deep breath of the crisp air and exhale the stifling heat of summer. We’re reminded of why we love living in the south.
Fall has all the lovely temperatures of spring without the coating of pollen. It makes you want to go outside again, and do… something. Clean out the jungle that was supposed to be the vegetable garden, deadhead the ratty zinnias, pull out the leggy petunias, and prune back the rampant shrubs. Go forth and tidy up!
Except for that last one. Now is not the time to cut back woody plants. It may seem like plants have two states: green and flourishing in warm weather or brown and dead-looking in winter. But their life is more of a cycle, a continuum from one state to the other, rather than a simple green versus brown situation. Plants are constantly adjusting and responding to the availability of moisture, nutrition, temperature, and hours of daylight.
Because temperatures in the southeastern US can be so erratic—75°F in February? That‘s become common. 70°F in July? Uncommon, but it happens—plants take most of their timing cues from the hours of daylight each day. Sunlight increases predictably from the winter solstice to the summer solstice, then lessens each day thereafter until the next solstice. Turn. Turn. Turn.
As the daylight decreases in late summer, plants prepare for winter by withdrawing moisture and phytochemicals from leaves and vulnerable tissues. Some plants produce abscisic acid, which allows the leaves to fall off. The green parts of the chlorophyll are dismantled leaving red, yellow, and orange pigments visible to give us the colors of autumn. These processes take a while. Even though it may be hot as blazes in September, the plants are preparing for winter.
When we prune a plant, the cut is a wound. No matter that the cut was made in the correct location, with a clean sharp blade, and for the right reason. To the plant, it is a wound that must be closed. In response, the plant revs up the mechanisms that seal wounds. It can’t rev up to heal and slow down into dormancy at the same time.
Pruning interrupts the dormancy process. When this happens, the plant may not have time to reach full dormancy before freezing temperatures arrive, making it vulnerable to cold damage or death.
So when do you prune? Like many questions about living things, the answer is, “It depends.” Here are some simple guidelines. 1) You can prune dead wood at any time. 2) Prune when plants are fully dormant. In middle Georgia, that’s usually mid-December to the end of January. This is also a time great to plant dormant woody plants. 3) Prune when plants are actively growing in early summer once they’ve had a chance to recover from winter by collecting sunlight with their new leaves for a while. 4) Prune spring-blooming plants like azaleas right after they finish blooming. That will prevent cutting off next year’s flower buds. It won’t hurt the plant to prune in winter, but you may not have a floral display the following spring.
What’s the worst time to prune? When plants are going dormant. That’s to say, right now and for the next two months.
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Donna H. Black writes articles, fiction, poetry, and more. A horticulturist by training and a writer by choice, she enjoys bringing facts about the natural world to readers. Follow her blog about writing at donnablackwrites.com and find her books on Amazon.com
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