3/10/2021; Adapted from Texas A&M AgriLife Extension Service – Galveston County
Freeze Damage FAQ
Winter Storm Uri inflicted widespread freezing damage to our landscapes. The following are common questions from homeowners. We hope you find this information useful as our landscapes repair over the coming weeks:
How do I know if my plant has been damaged and when can I prune off the dead tissue?
Different plants will show different damage symptoms. Discoloration, vegetation softening and or becoming dry and brittle are all signs of damage. Herbaceous plants like impatiens or begonias may collapse and become mushy. For herbaceous plants, continue to monitor to see if there is any green, whole tissue remaining. If there is living tissue remaining, remove the damaged, mushy portions to reduce the spread of disease. Try not to cut into living plant tissue.
With woody plants, scraping the bark with your fingernail will reveal the vascular tissue just below the bark. Healthy, functioning tissue will appear pale, and creamy in color. Cold damaged tissue will appear brown or black. Deciduous plants may still be dormant and leafless, and it will be difficult to assess freeze damage unless you scrape the bark. Wait until new buds along stems begin to swell and emerge from under the surface of the stem. Once new growth appears, prune off any obviously dead plant tissue.
Can I remove the damaged portions or tips of stems?
This soon after the freeze, you need to just wait and see. Even though it has been a few weeks after the freeze, our advice is to wait and monitor the plants response. Pruning damaged tissue exposes a new part of the plant to potential diseases, or late frosts and freezes. New growth and the tips of stems are the most sensitive to frost damage. It is tempting to remove this damaged tissue, and your patience not pruning allows vegetation to grow and providing a visual guide where to prune.
Should I fertilize?
Discontinue fertilizing until landscape plants have resumed active growth in the spring. The use of fertilizer at this time may stimulate new growth, which is susceptible to cold injury from late frost or freezes.
My St. Augustine lawn has turned totally brown. What do I do?
St. Augustinegrass is dormant and will appear brown during an average winter season. Longer daylength and warmer spring temperatures promote active grass growth, and early April is an appropriate time of year to begin annual lawn fertilization. Fertilization is not warranted at this time. Discontinue pre-emergent herbicide application this season; pre-emergent herbicides suppress root development in target spring weedy species and will provide the same action to grasses that are currently in recovery post freeze. Discontinue use of ‘weed and feed’ products. These are combination of fertilizer and pre-emergent herbicides, and each chemical should be applied independently at different times of the year.
Lawns generally do not require as much irrigation during winter months and adjust your watering schedule based on seasonal rain events. Resume mowing in later March or early April and at the appropriate height of 3 to 4-inches for St. Augustinegrass, allowing the grass time to recover.
What about my citrus trees?
Hardier growth on mature trees that have not been seriously damaged may rapidly shed dead leaves. If the dead leaves remain on the plant, this is an indication that branches have been seriously damaged. You can scrape the bark as described above to monitor for living tissue. Sometimes branches sustain cold damage, causing the bark to split. A young citrus tree may appear affected along the trunk, and it is best to identify the graft union, a visual swelling or junction where the fruit-producing part of the tree was grafted onto a rootstock. Remove any new growth emerging below the graft union as the vegetation will be non-productive for your purposes.
What about palm trees?
New growth on palms appears as a green spear emerging at the top of the tree. If this growth declines, the palm dies. The base of the spear leaf is one of the least cold hardy parts of a palm. If you can reach it, tug on the spear and if it seems securely anchored with additional green canopy present, the palm has a good chance for recovery. Remove dead fronds only after signs of recovery, or as warranted for safety underneath the tree.
One common phrase from Aggie Horticulture is “learn to love ugly”. Your patience awaiting signs of recovery and new growth will pay off in the long run.