Dormancy | Gardening in the Panhandle

It’s Time to Plant and Prune!

by Daniel J. Leonard | Dec 9, 2020

The last several weeks have brought consistently cool weather to the Panhandle, with a few downright cold nights dipping well below freezing. Though winter isn’t officially here, that won’t happen until December 21^st, grass mowing season is definitely over and, if you’re like me and didn’t cover your raised bed garden on those nippy nights, vegetable growing has also slowed significantly. So, what are us horticulturally minded folks with cold-weather cabin fever to do? It’s time to take advantage of sweat-free temperatures, break out the shovels and pruners, and get to work in the landscape!

Master Gardeners demonstrate correct tree planting techniques.

The months of December through February are ideal times for planting new trees and shrubs. The reasons for this are simple. Days are short, rain tends to be plentiful, temperatures are cool, and plants are mostly dormant. While newly installed plants need water to become established regardless of when they are planted, demand for supplemental irrigation is significantly less in winter (one of our rainiest seasons) and the chances of a new planting dying from thirst is slim relative to warmer months. Also, planting in winter gives trees and shrubs several months of above ground dormancy to focus their resources below ground, recover from the shock of transitioning from a nursery container into your native soil, and produce valuable roots that will help it get through its first summer. Think about it. Would it be easier for you to start and finish a major outdoor project in July with one bottle of water to drink or in December with an ice chest full? Plants prefer the same!

Not only is winter perfect for planting, tis the season for pruning many species too, deciduous trees (those that lose their leaves in the fall) in particular! The first reason to prune these species in the winter is to give the plants several months to begin healing before growth resumes in spring and insect and disease pressure ramps up again. Many serious pests and diseases of trees are most active during warm, wet weather and all of them have easier access to attack trees through open wounds. Prune in winter to help avoid unwanted pest and disease infestations. Also, dormancy has conveniently knocked the leaves off deciduous species’ branches, allowing us a clear view of the tree’s crown and giving us the ability to make clear, clean, strategic pruning cuts. Proper pruning can help maintain a strong central leader that produces a stately, straight tree and remove dead and diseased branches that could cause problems in the future.

While planting in the winter is always ideal and we just outlined several reasons pruning now can be good, not all plants should be pruned when dormant. For instance, old-fashioned hydrangeas and azaleas that produce blooms from the previous season’s growth. Pruning these in the winter removes all the flower buds that would have bloomed the next summer and what’s the point of an azalea or hydrangea that doesn’t bloom? Also, many small trees and shrubs, like Crape Myrtle and Vitex, may never need pruning if you site them where they will have room to mature without encroaching on other plants or structures.

If you have any questions about planting trees and shrubs, what, when, and how to prune, or any other horticultural topic, please contact your local UF/IFAS Extension Office! Enjoy the weather and happy gardening!

The Secret Life of Plants

by Taylor Vandiver | Nov 11, 2014

As winter approaches, short days and cool temperatures cause many plants to slow down and enter a suspended growth phase known as dormancy. Dormancy in plants is similar to the way bears hibernate during the winter. You may be asking yourself what is dormancy? And how can I get in on that? Well, to be honest, there isn’t an all-encompassing answer. It seems that plants (and bears) are keeping that secret all to themselves.

Fall foliage of Florida maple. Photo courtesy UF/IFAS.

Now that winter is indeed coming, deciduous plants start to breakdown proteins and other chemicals in their leaves and store them in the buds, bark and wood for growth next spring. Many deciduous plants lose their leaves as they become dormant, such as maples and dogwoods. Evergreen plants such as pine trees and camellias keep their leaves all winter.

There are actually two types of dormancy during the winter. One is called endo-dormancy. In endo-dormancy, the plant refuses to grow even under hospitable conditions. In endo-dormancy, something inside the plants is inhibiting growth. The other form is eco-dormancy and occurs when the plant is ready to grow, but the environmental conditions are not favorable (usually too cold). Short days and freezing temperatures in the fall induce endo-dormancy in the plant, which occurs first.

Shumard oak showing off its fall colors. Photo courtesy UF/IFAS.

As the plant enters endo-dormancy, it tracks chilling hours to chart the passage of the winter. Chilling hours are the time when temperatures drop below 45 degrees Fahrenheit. The number of hours required for chilling varies for different plants. Many people think the plant is tracking hours below freezing. However, hours below freezing have no effect on chilling, but will increase cold hardiness. If warm weather occurs before the plant completes its chilling requirement, no growth occurs. Chilling and endo-dormancy normally prevent plants from beginning growth during warm spells in the middle of the winter. Not all hours above freezing are equal. Temperatures between 35 and 45 degrees Fahrenheit seem to be most effective. Temperatures just above freezing and above 50 F are less effective and temperatures above 60 F often have a negative effect on chilling.

After a plant has checked off its chilling hours it is no longer in a state of endo-dormancy. It is now in eco-dormancy. The plants are dormant only because of cold temperatures. Warmer weather will cause plants to yawn, make that final stretch, and begin to grow. Growth first becomes apparent when buds swell and then green tissue emerges from the bud. However, plants actually begin growing before we notice their swelling buds. So this winter when your plants start to shed their leaves don’t be frightened, they may just be taking a much deserved rest in preparation for a brilliant show come spring.

Please contact your local extension office for more information.