When temperatures drop down to freezing or below freezing, plants that are not adapted will die back to the ground or unfortunately die altogether. Most tropical plants do not like drafts and temperatures below 40F. The water in these tropical plants expands and bursts the cell walls because they do not have enough antifreeze in their tissues.
When plants begin to thaw out, you may be able to tell if they made it. Plants that die back to the ground can re-sprout in the spring. Evergreen trees and shrubs can lose leaves and look dead, but they normally flush back out. Remember to remove any dead or broken branches, but avoid heavy pruning until the end of February or early
March.
Signs of cold damage can be confusing because some damage may not be evident until months later. Leaves and tender shoots exposed to freezing temperatures can appear water-soaked and wilted. The tissues will usually turn black within a few hours or days. The tips of narrow-leaved evergreens may turn uniformly brown. Broad-leaved evergreens often have marginal leaf burn. Reduced flowering is common in the following season. Bark splitting damage occurs when the stem or bark splits near the base of the plant due to sudden changes in temperature. If damage occurs at the crown of the plant, it may not survive. A frost crack is a long, deep, narrow crack running up and down the trunk of a tree. The crack is normally on the south or southwest side of the trunk. Frost cracks occur when the sun warms the trunk in the winter, causing the tissues to rapidly expand or when buildings block the sun. At sunset, the temperature of the trunk
drops quickly and the trunk contracts. Trees can be wrapped with paper tree wrap or burlap to prevent frost cracks. Wrap from the ground level all the way up to the first main branch.
Normally winter precipitation is enough to keep roots alive on established plants. If there is inadequate rainfall, keep plants watered. Winter is a great time to test the soil to see if any nutrients or lime needs to be added. Generally, you do not add fertilizer until April when plants are flushing out and needs those nutrients for growth. Nitrogen is not needed in the winter. Always follow the recommendations on the soil test results.
Organic matter and mulch can be added during the winter. Mulch and compost are great soil conditioners. They help to moderate soil temperatures, hold moisture, supply nutrients and prevent erosion.
Pine straw and pine bark mulch are great choices for mulch. Remember to keep pruning to a minimum, water as needed, check for pests and any damage. Follow the soil recommendation from the soil test, add compost and mulch to keep plants looking good. Cold damage is hard on plants, but good plant choices (right plant, right place)and good planning can help avoid future heartaches.
For more information on cold damaged plants, please visit the Home and Garden Information Center website at hgic.clemson.edu. Tune in on Tuesday nights to watch “Making it Grow” at 7pm on SCETV or mig.org. Email Outen at callenb@clemson.edu.
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