Master Gardener: Temperature ups and downs wear on plants

Published: Thursday, January 9, 2014 at 06:31 PM.

The most important thing you can do to minimize cold damage to your lawn and landscape is to prune and fertilize at the appropriate times of year. Cold hardiness is reduced in trees and shrubs following pruning. Trees and shrubs pruned just before a cold snap are more likely to be damaged than those pruned later in the winter when extremely cold temperatures are less likely. For this reason, it is better to wait until late February or early March to prune evergreens and summer blooming trees and shrubs such as butterflybush, Vitex, crape myrtle, and Knockout roses. Remember to wait until after they bloom to prune spring blooming shrubs such as azaleas, Indian hawthorn, and hydrangeas, to avoid removing their flower buds.  

Applying nitrogen containing fertilizers to lawns and landscapes in winter can increase cold damage by encouraging growth to begin too early. To avoid cold damage, wait until March before fertilizing landscape beds and trees. Using slow release fertilizers such as Osmocote or organic fertilizers such as Plant-tone further reduces the risk of cold damage. For lawns, wait until late April before applying any fertilizer.

If a sudden drop in temperature is expected, plants that are prone to cold damage such as sago palms can be protected by being covered with a quilt, sheet, or special synthetic fabrics made for frost protection, such as Reemay garden blanket. When covering plants, be sure they are covered completely and the cover extends to the ground to trap in heat from the soil. Also be sure to remove any coverings the next morning once temperatures rise above 32. Watering plants deeply a day or two before very cold weather can help reduce damage as well, since moist soil holds more heat than dry soil. This is only necessary if soils are dry. Keeping soils too wet through the winter can increase cold damage to plants.

Learn more

To learn more about caring for your garden and landscape, visit where you can submit questions via the ‘Ask an Expert’ link, or contact your local Cooperative Extension center by phone: If you live in Pender County, call 910-259-1238; in New Hanover County, call 910-798-7660; in Brunswick County call 910-253-2610.


Charlotte D. Glen is the horticulture agent with the Pender County Cooperative Extension of NC State University, College of Agriculture & Life Sciences. She can be reached via e-mail at

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