Rx for Cold Damaged Plants

As temperatures dip down to freezing and below freezing, plants that are not acclimated will die back to the ground or ultimately die. Most tropical plants do not like drafts and thermometer readings below 40 °F. They don’t have enough antifreeze in their tissues, the water in their cells expand and cell walls burst.

Once our plants begin to thaw out, we may be able to tell if they made it, but things that die back to the ground could re-sprout in spring. Normally evergreen shrubs and trees can also lose leaves and look dead, but they may flush back out. It is always acceptable to remove dead or broken limbs/branches. Even if a woody plant is badly misshapen, avoid heavy pruning until the end of February or early March.

Keep plants watered through the winter if there is inadequate rainfall, but generally, winter precipitation is enough to keep roots alive on established plants. Winter is a good time to test the soil to see if and when lime or other nutrients may be added. Generally, we don’t want to add fertilizer until April when plants are flushing and need those nutrients for growth. Always follow the recommendations on the soil test results. NOTE: Nitrogen is not needed during the winter.

Mulch and organic matter can be added at this time. Compost and mulch are excellent soil conditioners, and as they are incorporated into the soil, they help to moderate soil temperatures, hold moisture, supply nutrients and prevent erosion. Organic mulches keep beds looking tidy and give a finished look to the landscape. There are lots of choices of mulch, and the best ones are locally produced and sustainably harvested. For instance, pine straw and pine bark mulch are both locally and sustainably produced as they are byproducts of the timber and pulp industries.

If it’s necessary to replace landscape plants choose plants that are going to provide ecological services, be sustainably grown, require low maintenance, and easy on the budget. Ecological services include screening, shading, stormwater runoff prevention, habitat, and nesting for wildlife. Native plants are going to require a suitable site and proper installation, but after that, they should be easy to establish and maintain with little fertilizer, pest control, or supplemental irrigation.

Keep pruning to a minimum, water as needed, check for pests and future damage. Test your soil, follow the recommendations, add compost and mulch to keep plants looking good and replace as needed. Cold damage is hard on plants, but planning and good plant choices can help to avoid future heartaches. Happy New Year!

Information on pruning and care of plants after storms, see HGIC 2350, Cold Damage and Protecting Evergreens from Ice and Snow Damage.

Crabapple leaf covered in ice Laura Lee Rose, ©2020, Clemson Extension

Crabapple leaf covered in ice
Laura Lee Rose, ©2020, Clemson Extension

Camellia japonica buds and ice. Laura Lee Rose, ©2020, Clemson Extension

Camellia japonica buds and ice.
Laura Lee Rose, ©2020, Clemson Extension

If this document didn’t answer your questions, please contact HGIC at hgic@clemson.edu or 1-888-656-9988.

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