It has happened again this year! There has been 60 to 72 hours of 20 degree weather depending on your location. The events in December and January with extended, extreme cold weather has been very hard on many of your plant materials. The damages are severe because of the temperature fluctuation from warmer temperatures to extended freezing temperatures with no opportunity for plants to acclimate to the colder temperature. Once this happens, tender foliage and stems die. Plants turn brown, drop leaves, and often look like wet tissue paper due to cells in the plant bursting when the moisture in the plant cells turns to ice.
Unfortunately, all newly planted plant materials were very susceptible to this freeze damage. Thin barked trees such as lacebark elm trees, vitex and crape myrtle will have severe damage. There is a possibility that these plants will die back to the ground, especially the crape myrtle and vitex. Even heavier barked trees such as live oak and Chinese pistache will experience bark splitting from this kind of extreme weather.
Do not panic because most of your established perennial plants and shrubs are still alive. They will need to be cut back but you do not have to rush to do this. They will need to be cut back by the end of February to the middle of March to remove dead and damaged leaves and branches. If you have already cut back these plants, that is okay. I normally wait and give some time to be able to identify all the damage to the plant. Many times you will see splitting on the stems and that is also freeze damage. That will need to be removed in spring, if you see this damage. If you are unsure about what to remove, wait until spring greenup and cut back to new green growth.
I have had questions about covering plant material during periods of extreme cold weather. Covering only helps for a short period of freezing temperatures (four hours or less). When temperatures are in the 20’s or below for an extended period of time and especially with high winds, covering does not help. If you see that a period of freezing weather is expected, you should make sure plants are watered before the event.
To encourage new plant growth, fertilize all plant material – trees, shrubs and ground cover – in February. Unfortunately, living in Texas, we can always expect extreme temperature changes in the winter. This year has been a repeat of last year when unusually cold temperatures occurred for an extended period of time with wind and no time for plants to acclimate.