03/01/2021
Dealing with Freeze Damage on Plants
Greg Grant, Texas A&M AgriLife Extension Service
(February 27, 2021
Most roses in Tyler and East Texas appear to have taken a severe hit from the devastating freeze. At first glance it appears that most are going to die back to the snow line where they were insulated. The one pictured is the Earth-Kind polyantha, La Marne, in my dumpster bed at the Cotton Belt Bldg. Some, like hybrid teas, grandifloras, and floribundas are more cold hardy and others like teas, chinas, and noisettes are less cold hardy, so some types might freeze to the ground or even die. Bottom line, postpone pruning until you see what is alive and growing, then prune away all the dead stems, sprinkle a bit of lawn fertilizer and enjoy blooms on the new growth this summer and fall. Here my updated notes on the freeze and other plants.
There is no way of currently knowing the extent of the damage or whether your plants will survive or not. It will take weeks or months to know, if or when, they start to resprout and what part of the plant resprouts.
1. Evergreen Woody Shrubs, Vines, and Groundcovers (Asian jasmine, azalaeas, camellias, confederate jasmine, eleagnus, fatsia, fig ivy, gardenias, Indian hawthorns, ligustrum, loquat, loropetalum, oleander, pittosporum, privet, roses, sasanquas, sweet olive, Texas sage, wax myrtle, etc.): Wait until they start to resprout from the existing stems or the ground, then cut away dead and leave what is alive and growing. There will most likely be no blooms this year and all old foliage will most likely fall off. Many of these plants are from milder parts of southern Asia and simply aren’t used to zero degrees. Most broadleaf evergreens prefer milder climates while narrow leafed evergreens and deciduous plants are more adapted to colder climates.
2. Palm Trees and Sago “Palms”: Many will be damaged or dead but do nothing but cut off the dead fronds for now. It will take months to see if they resprout. Historically the only palms reliably cold hardy here in northeast Texas and the only ones to survive zero degrees in the 1980s were Mexican/Texas sabal palms, Brazoria palms, dwarf palmettos, and a number of windmill palms. All others froze and died. Sagos aren’t true palms, are less cold hardy, and back then were only cold hardy from I-10 south.
3. Perennials: Cut away the dead mush (wait until April 1 if you can stand it) and wait till mid spring to see what comes up. Many perennials are cold hardy but many we grow in the South are more tender and tropical (confederate rose, Mexican heather, Mexican petunia, and lots more) and may not make it when the ground freezes.
4. St. Augustine and Centipede lawns: There will possibly be dead areas and freeze damage. Mow as normal but avoid pre-emergent herbicides which can damage injured grass. Do not fertilize until nights are warmer in mid-April and do not water until June, July, and August, once per week, one inch per application. Watering in the spring contributes to gray leaf spot and brown patch. Most folks water too often and cause their own problems.
5. Crapemyrtles: There will be different amounts of damage on different cultivars in different microclimates. Don’t do anything until they start to sprout then cut back to where new growth is occurring, even it’s at the ground. They will grow back vigorously. In the 1980s Lagerstroemia fauriei froze and died, ‘Natchez’ and many hybrids froze to the ground, and there were varying degrees of damage to most older indica cultivars.
6. Fruit trees: Most are cold hardy except citrus, pomegranates, olives, and figs which will have varying degrees of damage and death. Once again, do nothing for now and prune back to live growth when they sprout. Open flowers and fat buds on blueberries, peaches, and pears froze but the trees should be alive and sprout as normal. Unfortunately fruit production will be limited. I’d think blackberries will be fine.
7. If plants are green and not withered, they are most likely fine. It all has to do with their evolutionary and geographical genetics as to whether they can survive zero degrees. Bust just because they are brown doesn’t mean they are dead. It’s possible that the stems or roots may still be alive. Give them time.
8. Most deciduous plants will be fine although they may have lost their bloom buds. Spireas appear fine. Mophead and lace cap hydrangeas may have different degrees of damage. Once again, only prune away what is dead once they sprout. Oakleaf hydrangreas are probably fine.
9. Most conifers including pines and cedars will be fine although they may be damaged and broken from snow and ice. Saw off the broken branches close to the truck or nearest major branch wherever you can.
10. Bulbs (corms, rhizomes, etc.): Although the foliage has been damaged and many blooms lost on spring bulbs, most should survive with possibly reduced bloom next year due to less foliage this year. I wouldn’t be surprised if many heirlooms produced more foliage and bloomed almost normal next year. Note due to their geographic genetics, narcissus are the least hardy, jonquils more hardy, and daffodils the most hardy. Some daffodils may still bloom. However anything that already had buds won’t bloom this year. Tulips seem OK. Spider lilies (lycoris) and oxblood lilies lost their foliage but will be fine with possibly reduced bloom this fall. Cannas and Hymenocallis may have rhizome and bulb damage if the ground froze.
11. Live oaks: All foliage will be lost which would have been lost when the new foliage came out in spring anyway. There however many be varying degrees of damage including death like there was in Dallas during the 1980s when all the bark eventually popped off, but once again nothing you can do right now but take a cold tater and wait. Live oaks are coastal trees not used to zero degree weather. Friend Neil Sperry says they’ll be fine so we’ll all hope for the best!
12. Herbs: Many herbs like rosemary and lavender will be dead and will need to be replaced, certainly those in pots which are always less cold hardy than those in the ground. Some rosemary cultivars are more cold hardy than others but very few can survive zero degrees. Most herbs are Mediterranean and prefer mild winters and dry soils.
13. Pines: Pine in some areas have turned brown. This is mostly likely just freeze damage to the needles but the buds and stems should be fine. Our native pines along with all our other native plants have learned to survive periodic Arctic blasts. Note that nature made sure that short leaf pine occurred further north, loblolly pine with medium length needles occurred farther south, and longleaf pine occurred the most south. It’s all about holding up to ice and snow but all have always been cold hardy here for thousands of years.
14. Vegetables: Most were frozen and will need to be replanted including onions, potatoes and cool season greens. It’s still too early for tomatoes and peppers and I wish folks would quit putting them out for sale. Never plant them before March 15.
15. Native Plants and Wildflowers: Most are perfectly fine as they evolved to deal with periodic Arctic blasts and blue northers.
16. House plants (aloe vera, Christmas cactus, croton, diffenbachia, peace lily, philodendron, ponytail palm, sanseveria, etc.): If they were left out outside, they should be dead, even if covered. Count it as a minor miracle if not. These plants aren’t designed to withstand 32 degrees much less 0!
17. Succulents (Agaves, opuntia, manfredas, yuccas, sedums, etc.): Some of these guys are very tender and will be dead while others are more-cold hardy and will be fine. When it warms up and the mush dries, peel it away and see what comes back.
18. Tropicals (allamanda, bananas, bougainvillea, elephant ears, esperanza, mandevillea, purple fountain grass, tropical hibiscus, etc.: Cut away the dead mush and stems (wait until April 1 if you can stand it) and wait till mid spring to see what comes up. The general rule on tropicals is if the air freezes the tops die and if the ground freezes the whole plant dies. Those left outside in pots are probably dead and should be replaced in April/May when the nights warm up.
19. Bamboo: Most have at least top damage. Some, like timber bamboo are cold sensitive and will be dead; some types like golden bamboo and Green Goddess will most likely freeze to the ground and resprout, and a few like our native switch cane will be unscathed. All you can do is cut the frozen dead stems to the ground now and wait to see what comes up. You’ll know by early summer whether they are growing back or not.
20. Ornamental Grasses: With the exception of purple fountain grass, lemon grass, napier grass, and vetiver, most are cold hardy and will sprout back from the crown. Go ahead and cut them back to the crowns now and wait until early summer to see what comes back.
21. Genetics, provenance, and acclimation: Cold hardiness has much to do with the genetics and evolution of a species (Who’s your daddy and where are you from?); what part of the historic range the seed sourse was from (live oak seed from colder Virginia or live oak seed from warmer South Louisiana); and how warm it was and how actively the plant was growing before it froze (plants freeze much more easily when they are growing than when they are dormant). This explains why National Arboretum crapemyrtles never froze in Washington D.C. and more northern climates but have frozen numerous times in Texas over the years.
There is absolutely nothing you can do to speed up this freeze damage/healing process. Watering, pruning, or fertilizing won’t make it happen any quicker. Most work now is purely cosmetic. The solution is warm nights, warm days, and longer day lengths. Once the plants start to grow (or not), we will know the answer and what parts to cut away or which plants to replace. Some damage doesn’t show up for months and some plants that appear dead come back to life from the root system. Some plants with green stems like roses will show what’s dead even quicker and can be cut back sooner.
For more information on dealing with the freeze damage, visit the Aggie Horticulture page, the Smith County Master Gardener page, and Neil Sperry’s GARDENS page.
