Freeze Damage to Plants

I am sure everyone is anxious to know what damage the extreme cold temperatures have done to our landscapes. Unfortunately, it is too early to tell in most cases. You will hear me repeat this, I am certain, but “time will tell”. I know it is difficult to have patience, but because there are so many factors that can influence how a plant might be affected, that is exactly what we will have to do. Try to get used to the “ugly landscape”, as we really don’t have a choice!

So, what are the things that can influence whether a plant will survive a severe cold event?

*Exposure: Plants on the north or northwest side of a structure will be the most exposed to the cold. Wind may also play a part in winter damage, and most of our winter wind in Central Texas comes from the NW.  Plants located on a south or southeast exposure may receive some protection from severe cold. That is why we recommend planting “marginally winter-hardy” plants on the S-SW side of the house.  A north-facing slope is considerably more susceptible to winter injury, as snow and ice will be slower to melt and the ground will be slower to heat up.

*Low-lying areas are subject to colder temperatures than adjacent higher areas.

*Snow and ice coverage of lawns, soil and plants does have an insulating effect if it happens BEFORE the freeze. Most of us had ice and snow before the bitter cold. With no snow or ice, the cold temperatures can kill the crown of the plant, especially on lawn grasses, as air temperature is colder than snow or ice temperature. In this respect, we may have lucked out.

 

 

 

 

 

 

 

*Well-hydrated plants are usually more tolerant of cold, as moist soils have a higher heat capacity than dry soils.

*Duration: The more prolonged a freeze, the greater the potential for injury.

*Age of plant and stage of growth: Young, recently planted trees and plants are more sensitive to cold injury. New flushes of growth are likely to be affected.

*Trees and plants that are not protected by surrounding trees and plants, but stand alone, will be more sensitive to cold injury. Understory plants are more protected and may have less injury.

*Species of Plant: Cold temperature tolerance varies widely between species. Determine the cold tolerance Zone of the specific species to see if their cold tolerance was exceeded. Consult the  USDA Plant Hardiness Zone Map for the most accurate information on low temperature tolerance. 

*Timing of the freeze: Early freezes, before the plants have had a chance to “harden-off” properly, will affect plants more than those that have been receiving a gradual “hardening-off” and have become acclimated to the cold. Central Texas has highly variable winter temperatures, which makes it difficult for many species to enter dormancy. Plants that have begun to “emerge” in early spring with new growth will be more susceptible to cold damage.

*Plants in pots and raised beds will be more likely to have root damage or death from freezing temperatures than those planted in the ground. Ground soil usually provides enough insulation to moderate temperatures in case of a freeze, especially if it is moist, but if above ground in a pot or raised bed, this is not the case. Location and species play a factor in freeze damage, but I would expect the root damage to most plants in pots to be extensive.

 

 

 

 

 

 

 

 

 

What Can We Do After a Freeze?

It is more important to know what NOT to do after a freeze!

*DO NOT prune plants or remove plants until you have determined the extent of injury. (It is ok to prune broken branches, of course. Be sure to make the cut in the appropriate place to avoid insect and disease entry into the tree.)

*Exception: Plants that have gone to “mush” may be removed or trimmed back. These include succulents, Agaves, tropical plants and herbaceous perennials. The longer you leave them, the smellier they will get. Any annuals that have collapsed should be removed. Perennials such as Society Garlic may be clipped off at the soil line, as they may come back from the roots.

 

 

 

 

 

 

 

 

*A broad generalization: Plants that end up shedding their leaves have a greater chance of recovering from a freeze than those that hold onto dead leaves. Shedding leaves can indicate living stem tissue, and depending on species, may offer a ray of hope. Plants that hold onto leaves have stems that are  likely dead.

 

 

 

 

 

 

 

 

* “Bowing of branches after the ice storm”:  Trees with bowed limbs may recover after the ice melts.  However, bowing can cause internal cracks or vascular system damage and limbs may not return to their normal position. Limbs may be permanently bent and therefore may require removal. I have been asked if bracing or staking may help these limbs, and my answer is “maybe”. We unfortunately cannot see the damage inside the limb, and would recommend consulting a Certified Arborist to assess the options.

*Vegetable Gardens: If you have lost vegetable plants to the freeze and are past the “window” for recommended planting of that variety, just move on. Late plantings are seldom successful. Onion tops that have “melted” can be snipped off. They may re-grow. If potatoes had started to sprout and leaves turned black, trim them off just below ground and wait for more to appear. Any veggie plants that have turned to mush should be clipped off at the soil line and composted. Do not leave them in your garden as they will harbor fungus and bacteria.

 

 

 

 

 

 

 

 

*Do not fertilize plants or lawns until they have begun “greening up” this spring. You can do more harm than good by applying fertilizer too early.

*St. Augustine lawns will likely be damaged by this freeze. Floratam is the least cold tolerant variety, but all St. Augustine varieties are likely to be affected. Be patient. Do not apply pre-emergent, post-emergent herbicide or fertilizer until the lawn has shown that it is “coming back” well. Bermuda and Zoysia lawns will require a “wait and see” approach. The ice/snow cover was beneficial as it captured ground heat and acted as an insulator. It is possible that the crown of the grass survived and may make a decent recovery. We are in untested times.  Age of lawn, exposure, moisture content of soil and underlying factors such as compacted soil, disease, etc. will influence recovery.

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Plant-Specific Recommendations:

We cannot list all the plants that may have been affected, but we will try to touch on as many as possible.

Perennials:                                                                                                                                                                                     

Bicolor Iris: These appear to have been hit pretty hard. They are Zone 8b, so many will likely not come back. Watch for new growth before cutting back, but in my experience, they will not come back as full and as pretty as you’d like and are probably worth replacing.

 

 

 

 

 

 

 

Bulbine: As a Zone 9 plant, I would not expect these to come back. They have already “gone to mush” and can be removed.                       

Canna lilies:  These are Zone 7-8 plants, so they may come back from the roots, especially if they were already dormant when the freeze hit. Watch for new growth to emerge. Remove the mushy growth if you haven’t already.

Chile Pequin: Woe is me. The Chile Pequins are frozen in my yard. I am hoping that it might come back from seed, but if not, I will replant. It is herbaceous in Zone 8 in typical winter.

Duranta: Well, a lovely plant, but at Zone 10 it should be treated as a tropical here.

Elephant Ear: Colocasia esculenta varieties are mostly Zone 8, and all the ones that I have seen have mushy bulbs, tubers, and rhizomes. Most Alocasia varieties are Zone 9 and are not expected to come back. If yours are not mushy, wait for new growth to appear. My experience with these is that they are very slow to come back from less severe freezes.

Esperanza:  Even if well-established, this Zone 8b plant probably will not come back. Like the Pride of Barbados, it will be late to come back if it is going to, so patience is key. Cut to the ground in mid-March and wait.

Holly Fern:  If these Zone 6 plants were watered and well-mulched, there is a good chance that they will return. Since they are shade plants they are probably understory, and that will help on survival. Wait for new growth to emerge before cutting back.

Jerusalem Sage: Although this is a Zone 4 plant, I think we will see losses this year due to the warm winter we experienced over the winter. It did not have a chance to harden off before this cold. It does not regrow well if cut back hard, so wait to see if it puts out new growth before making any decisions.

Lantana: With the exception of Texas Lantana (Zone 8), the majority of our hybrid Lantanas are only hardy to Zone 9 or 10. They are not likely to come back this year. They are grown as annuals in the north.  I would replace them when it warms up. Few plants give as much color with such consistency.

Mexican Bush Sage, Mystic Spires Salvia:  Both are Zone 7, so chances are better for them to come back, especially if mulched and watered before freeze. It is ok to remove frozen growth now.

Mealy Blue Sage: Although a tough perennial, these are Zone 8, so again, wait and watch. They have been killed in previous cold winters.

Mex. Mint Marigold:  I have also lost this Zone 8 perennial in less cold winters. Remove the growth that is mushy and wait to see.

Mexican Firebush: Although this is Zone 8b, it rarely comes through a cold winter here. Location is key. Leave it until at least late March.

Orange Zest Cestrum: I am worried about mine coming back this year. Even though it is “technically” Zone 8, unless it is in a protected site, it may not return. If it does, it will usually come back from the ground, so if you see new growth from the base, cut it back to the ground.

Plumbago: As a Zone 9 plant, only plants that are well-established and in a protected location will likely come back. If they were mulched and watered before the freeze and in a S-SW location, it may be worth the wait. I am not expecting mine to come back, but hey! you never know!

Pride of Barbados:  Even if well-established, these Zone 8 plants may not return. You can cut them to the ground in mid-March. Since they never show growth before the ground gets quite warm, just be patient. Replacement plants won’t be available until late spring anyway, so no need be in a rush.

Salvia greggii: Many will probably come back from the roots, as they are a Zone 6 plant. If they were in active growth, newly planted or quite exposed, they will be less likely to come back. Wait to cut back until you see new growth at the base. They can come back from a hard prune.

Society Garlic: This Zone 7 plant has gone to mush and should be clipped off at the ground. Wait for new growth to appear before you count them out.

 

 

 

 

 

 

 

 

Thryallis: These are usually hard to kill, but this might be the year. Wait for new growth to show, as these can come back from the ground if you see growth at the base. A Zone 8b plant. If it was in a protected location and mulched, there may be a chance.

 

 

 

 

 

 

 

 

Var. Flax Lily:  Zone 8a, but I’ve lost these to less cold winters. It is not likely they will have survived this winter. They are worth replacing,  as they are deer resistant and tolerate shade, which is rare.

 

Palms:                                                                                                                                                                                              

Mexican Fan Palm, Pindo Palm and Mule Palm likely won’t come back from this freeze. The Mediterranean Fan Palms in my neighborhood do not look like they will survive. We are keeping a careful watch on the more winter-hardy Windmill Palms and Florida Sabal Palms. Even our native Sabal minor has some damage, but looks a bit better if it is planted understory. Location will have a lot to do with survival. If the apical meristem is frozen, the palm will not survive. The apical meristem is located under the “spear leaf”, or newest leaf that has not yet unfolded. If you pull gently on the “spear leaf” and it pulls out easily, the palm is most likely gone. There is a slight chance that the meristem below the “spear leaf” is still alive. If you want to give it a chance, spray that area with a copper fungicide immediately after the freeze (if you missed this window it is probably too late) and once again two weeks later to prevent the area from rotting. Then wait. It can actually take several months to determine if a palm is going to recover or not. My feeling is not very positive this year about most palm trees. We are waiting to see how our suppliers “wintered” this storm, as it is likely to affect palm availability in the near future.

Sago Palms are not actually palms, nor are they likely to survive a freeze such as this, unless they are in a very protected area. Wait until at least March to remove dead fronds. Then wait. Patiently. They can be very slow to come back. I think only those that were in a very protected location may return. Maybe. Plants in pots would not be expected to survive unless they were brought inside.

 

 

 

 

 

 

 

 

 

Ornamental Grasses:                                                                                                                                                                 

Our Ornamental Grasses have different hardiness Zones as well, and the best thing we can do is wait. Watch for new growth from the ground before cutting them back. If they were already cut back prior to the freeze, they lacked the insulation that the dead growth can give to the crown of the plant and may be less likely to come back. Now you know why we say to wait until late February to early March to do the bulk of your pruning!

Roses:                                                                                                                                                                                               

Roses are generally considered cold hardy in Central Texas. However, since Central Texas has had a relatively warm winter this year, many were not “hardened off” and some even showed new growth and blooms before the freeze. This all adds to the outcome.

Again, protected location, maturity of the plant and mulch and water application before the freeze all contribute to survival. Wait to see new growth emerge and prune back to healthy tissue. Roses are resilient, and unless it is a grafted rose like a Hybrid Tea that does not come back “true” below the graft, we are hoping that most healthy roses will be ok. Wait to prune until you see new growth.

Shrubs, Evergreens and Small Trees:                                                                                                                                 

Anacacho Orchid: Do not prune until new growth emerges. These trees can be cut to the ground if there is still life in them, and new trunks can be selected to form a new multi-trunk tree. Expect dieback at the very least.

Abelia: Most Abelia are hardy to Zone 5, and often die to the ground in those locations. Watch for new growth to determine extent of pruning.

Arizona Cypress: I have seen little damage to these Zone 7 trees, so I am hoping for the best. Like all plants, keep a careful watch on the bark for splitting.

Bottlebrush: Zone 9 Little John and Zone 8 Scarlet Bottlebrush have succumbed to less severe winters. Zone 7 Woodlander’s Hardy deserves some patience, although the outlook is not too positive.

Boxwood: There are many different species of Boxwood, and although most are Zone 3, we may still see some bark split and even death of some plants. Again, our warm winter is to blame. Monitor for new growth and prune accordingly. Remove as little “living” growth as possible, as the plants will need this growth to produce carbohydrates for growth and recovery. 

 

 

 

 

 

 

 

 

Cherry Laurel: The Cherry Laurels in my neighborhood look like they came through this freeze pretty well, although some have shown some freeze damage. They are Zone 4 trees, and unless they were newly planted or had new growth on them, they should be ok. Wait to prune until you see new growth this spring.

Common Tree Senna: These probably will not come back, but it depends on exposure. They are normally evergreen in Zone 8 winters. Scratch the trunk at the base to see if bark “slips” and watch for bark splits. I have not seen these come back from the roots.

Dwarf Yaupon Holly: These Zone 7 shrubs may turn brown and lose their leaves, but I would expect most to leaf out this spring. A light shear after leaves appear will help keep them full.

Natchez, Tuscarora and Muskogee Crape Myrtles: These were damaged or killed in the ’83-’84 freeze. It will depend on their exposure and whether the roots were killed. Wait until new growth shows, cut them back to living tissue or to the ground and be patient. Freeze-damaged trees can take some time to come back, but Crape Myrtles can be quite resilient. Other varieties are generally more winter hardy, and will require monitoring and pruning of dead twigs/branches when they leaf out.

Desert Willow: These trees are prone to breakage from heavy ice or snow. I have seen them rally after being pruned heavily from ice damage, so don’t give up too soon. Remove broken limbs now but wait until you see new growth to do any major pruning. They may be late to leaf out.

Desert Museum Palo Verde:  I am sure that these will have a bit (or more) of dieback. They are Zone 8 trees (10°F). Some will have broken branches, which may be pruned now. Wait to see new growth to decide how much to prune. 

 

 

 

 

 

 

 

Encore Azalea: Hardy to Zone 7, so I am hoping that these will just defoliate and come back. If they were in pots the chances are not as good. If they were not putting on new growth or newly planted, and were in a protected location, they will probably be fine.

Evergreen Sumac: I have never seen these exposed to temperatures this low. Many in the area have turned brown, but some, especially understory, are still green. Again, age, condition, exposure, and genetics at work. This will be a “wait and see” as well, and I am hoping that when they begin to put on new growth, we can prune them and they will revive. If the brown leaves defoliate, that is a better indication that the stems are alive. Some of mine are “scratching green”, but some are not. If new growth arrive this spring, prune accordingly. We are in uncharted territory with this one. 

Fig Trees: Do not give up too early, especially if they were somewhat protected.  Watch for new growth at base, and if roots survived, it may come back slowly from the roots. They are tender, so don’t be too surprised if they don’t come back.

Indian Hawthorn:  Generally cold hardy to Zone 8, these have taken a hit this year. Leave them until new growth appears. I think location and variety will have a lot to do with which ones survive.

Italian Cypress: Many of these now have brown foliage, but we are hopeful that when they flush out they will recover. They are not root-hardy,  however, and do not come back from the roots or flush from a hard prune into woody growth. Although they are Zone 7, this is one that we will watch.

 

 

 

 

 

 

 

 

Ligustrum, Waxleaf and Japanese: Both Waxleaf and Japanese Ligustrum are hardy to Zone 7, but the winters of ’83-’84 and ’89 killed a lot of them. We will keep our eye on these for now. Don’t prune til you see new growth.

Ligustrum, Chinese and Sunshine: Ligustrum sinense is hardy to Zone 6b, so I’m pretty sure these will just defoliate and leaf out in the spring. There may be some dieback, but established plants will probably get away with a light pruning.

Japanese Camellia:  Since most of us grow these in pots, they will most likely need to be replaced. If they were in the ground in a protected S-SW location, they may revive. Zone 6-7. The warm winter may affect how hardened off they were.

Japanese Yew: I have seen some with little damage and some that are completely brown. Some of these will not come back. They do not regenerate from roots well, so if the bark is “slipping” at the base, I would go ahead and remove them. If they still have green growth, wait for new growth to make decisions on pruning. Survival may depend on exposure, as plants in northern exposures suffered the brunt of this freeze. 

Junipers and other evergreens: Junipers will possibly show brown foliage, mostly towards the outside of the plant. This foliage is dead. Latent buds may grow and fill in, so wait until mid-Spring after you see new growth to lightly prune.

 

 

 

 

 

 

 

 

Loquat: Loquats have probably taken a hit this year. They do not come back from the roots, so if yours is dead to the ground and does not scratch green anywhere on the trunk, you can go ahead and remove it. If it was protected, you may have dodged a bullet.

Loropetalum: Although these evergreen shrubs are hardy to Zone 7, if they were newly planted or in active growth when this freeze hit, they are more vulnerable. At the least, they will defoliate. Wait for new growth to prune.

Oleander:  Marginally winter hardy here, but often dies to the ground in hard winters. This freeze may have done them in. Wait for new growth from the ground to appear to make the decision whether to remove or cut them back. It will also be slow coming back.

Olive Trees: Olives are marginally winter hardy here. Most varieties are Zone 7-9. Arbequina Olives are Zone 7, so that is promising. They are often frozen back or killed to the ground, but this may be the freeze that does them in. Watch for new growth before deciding on how far to cut back or remove. Lightly scratch the bark to see how far back it scratches green. If the bark “slips” it is not viable tissue. If they are not a grafted variety, they may be cut back to the ground if necessary and they will come back true to type.

Pineapple Guava: These Zone 8 subtropical plants really suffer when the temperatures go below 15°F. Unfortunately, they are also slow growing, so if they did survive this freeze, it will be a few years before they recover well. I do not expect many to survive. Wait to see new growth before pruning.  

Primrose Jasmine: Another one that could be dead to the ground this year, or even just dead.  It may come back from the roots, so wait to see new growth from the base before deciding whether to remove it or cut it back.

Sandankwa Viburnum: Wait to see if new growth emerges before pruning.  Scratch the bark at the soil line to see if it is green underneath. If the bark “slips” off like it is rotted, I would go ahead and cut them to the ground in March. It is possible they could come back from the roots. You can cut them back severely if showing green stems, but wait for new growth to arrive. I fear many will not survive.

 

 

 

 

 

 

 

 

Southern Magnolia: There are several varieties of Magnolia, some are larger than others. They are generally hardy to 5°F. Their evergreen branches may have broken in the ice and snow, and unfortunately, these trees do not “fill in” when parts of the tree are lost. Most of the ones that I have seen so far look pretty good. Again, check the trunk periodically for cracks.

Southern Wax Myrtle:  What a brittle shrub! The slightest amount of ice and they will break. Remove broken branches now but wait to prune back hard until danger of freeze is past in March. These can come back fairly well if cut back hard after new growth is emerging.

Sweet Olive: The leaves turned brown and fell off my Sweet Olive, and I consider that a good sign. Wait for new growth to appear before making decisions on pruning. Zone 8

 

 

 

 

 

 

 

 

Texas Mountain Laurel: These have survived freezes in ’83-’84 and again in ’89. We know that even the most protected ones will have had their flower buds frozen. I have seen a pretty big variance in damage, depending mostly on location. The understory trees seem to have fared better, but boy do mine have a lot of broken branches! This one we will “wait and see”, as I am thinking that most will defoliate at least partially. Once we see the extent of the damage, we can make a plan on pruning. Stay tuned.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Texas Redbud: These Zone 6 trees should be fine. Since they are deciduous and had already lost their leaves, I would expect them to leaf out this spring. You may need to prune dead branch tips.

Texas Sage: There are many different species of Leucophyllum, and most are cold tolerant to Zone 8. These have certainly taken a hit, and time will tell. If the bark splits, it is not a good sign, but I have seen them come back from stumps before, so be patient. Wait for new growth from the base or on the branches before cutting back.

 

 

 

 

 

 

 

Yaupon Holly: Most of these have brown leaves, unless they were protected or understory. So far, the twigs are green, so if they lose their leaves they will most likely leaf out again. A light trim after they start to leaf out will be beneficial. Zone 7.

Succulents:                                                                                                                                                                                     

Agave: Most Agave species are not hardy to the temperatures we experienced. If they have “gone to mush” go ahead and remove them. I have had questions as to whether the one “spear” leaf that is still upright indicates life, and my answer is probably not. Feel the base of that unfurled leaf, and if it is soft, go ahead and remove the plant. You will do better to remove these earlier than later, as bacteria and fungi proliferate on the dead tissue and makes for a smelly mess.

Cactus: I cannot list all the varieties of cactus here, as there are too many to address and we really do not have any experience with them in this low of temperature. If they remain solid, the news is good. If they “go to mush” you should remove them.

Yucca: Again, we have many species of Yucca in Central Texas. Some will be more winter-hardy than others. In general, I think the Hesperaloes, or Red Yuccas, will be fine, although I have seen leaf damage. The Yucca rostrata (Zone 5, or -15°F) will probably be fine as well. Other species we will “wait and watch”. Do not prune off frozen growth until you see new growth from the top. If the entire plant has “gone to mush”, I think you have your answer. If the bark on the trunked species “slips” when you rub it, then the trunk is dead. Some species may send up “pups”, so you might cut the plant to the ground and wait.  

Vines and Groundcovers:                                                                                                                                                         

Asian Jasmine: This evergreen ground cover is more winter-hardy than its relative Star Jasmine. Most plants will have brown leaves but can be mowed to 4”-6” and they should send out new growth in the spring.

Carolina Jessamine: This Zone 5 vine is pretty tough. If it is an established vine, watch for new growth to decide how far back to prune.

Coral Honeysuckle: Most Honeysuckles are hardy to Zone 4. We are hopeful that it will show signs of growth, at least from the base, but it will probably be later.

Confederate Star Jasmine:  This Zone 8 vine has taken a hit in past freezes, so I would not expect any but the most protected vines to survive. The variety ‘Madison Hardy’ Star Jasmine (Zone 7) is a bit more winter hardy, so be patient to see if it is going to return. Location will have an influence.

Fig Ivy: This might ? have a chance if grown on a south-facing wall and roots are mulched. Most of them have died in past hard freezes. If they do not show signs of re-growth from the roots by the end of March, it is time to re-plant.

 

 

 

 

 

 

 

 

Passion Flower Vines have varying levels of cold hardiness. Blue Caerulea is one of the most cold hardy at Zone 7, but ‘Lavender Lady’ is only Zone 9. Only the most protected of these will likely survive. Be patient, though, as they will be late to emerge. Watch for growth emerging from the roots.

Wisteria: Hmmm. I’m not too worried about this Zone 5 vine. It is hard to get rid of anyway, so watch for new growth from the ground at the very least.

Yellow Butterfly Vine: When well-established, these are pretty tough plants. They are rated for Zone 8, and the roots may survive if planted in a protected location. I have had mine defoliate in a fairly cold winter and die back by ½ in a very cold winter. I’m not sure about this year! Newly planted vines are less likely to survive. Wait to see.

 

Tropicals:                                                                                                                                                                                        

Bougainvillea, Mandevillea, Tropical Hibiscus and other Tropicals: Since these are Zone 10-11 tropicals, if they were planted in the ground I think it is safe to say you can pull them out now. Even the winter-hardy bananas are likely lost this year. Plants in pots, if not protected, will need to be replaced.

Citrus:                                                                                                                                                                                              

Citrus: I grow all my Citrus in pots just for winters like this! Yes, it is fairly safe to grow Arctic Frost and Orange Frost Satsuma in the ground most years, as they are not a grafted variety and will come back “true” from their root stock if they freeze back. But even they may not survive this winter. Meyer Lemons are sometimes grown in the ground here in a protected exposure, although they are a grafted variety and will not come back “true” from below the graft. You can scratch the bark at the ground level to see if it “slips”-if so, it is probably not coming back. If it scratches green, do nothing until new growth shows. If the new growth is coming from below the graft, replace the tree. And consider keeping it in a pot.

 

Fruit Trees:                                                                                                                                                                                    

Apple, Peach, Pear, Plum, Nectarine, Apricot and Oriental Persimmon are hardy to Zones 4-5 if well-established.

Jujube and Nectarine are hardy to Zone 6 if well-established, and Pomegranate to Zone 7.

We really do not know what to expect from this event. As mentioned before, it will depend on location, age, general health, moisture level in soil, whether they were exposed to prior cold temps and stage of growth of the trees. Blossoms will have frozen, but some young flower buds will probably survive.

The biggest issue with young fruit trees will probably be “frost cracks” in the trunk. This is caused by wildly fluctuating temperatures and occurs on many thin barked species. Fortunately, callus tissue often covers the cracks, especially if they are not too deep. Do not spray them with tree paint. Keep the trees healthy and wait.

Shade Trees:                                                                                                                                                                                  

Deciduous trees will generally fare better in the winter than evergreen trees, as there is little movement of water into the trunk from the roots and the vascular system is less likely to freeze. Many trees have adapted with narrower xylem tissue that is also more resistant to freeze. That said, this freeze was unprecedented and without a gradual acclimation, so we are in new territory.

Live Oak:  Our Live Oaks look pretty sad right now. The younger, more recently planted trees perhaps look worse. This was a VERY low temperature for them. They really don’t like it below 20°F, but they saw it in ’83-’84 and again in ‘89. But not THIS cold! I think we can expect them to defoliate fairly soon. Every location will be a different story according to microclimate, age, genetic differences, etc. Some will probably come back sooner and better than others. A healthy tree is likely to recover better than a stressed tree, and trees in groupings will have been better protected than single trees. Broken branches should be removed and painted, but no other pruning until July.

 

 

 

 

 

 

 

Bur Oak: This is one hardy oak! Grown in Zone 3 with no issues, and the sturdy branching and strong wood make it less susceptible to breaking in ice storms.

Mexican White Oak: Although this tree is rated a Zone 7 tree, it has taken a “hit” in previous cold winters. This is one to “wait and see”, as the ultimate outcome may not be evident for weeks to months. We are hoping the leaves will shed and trees will leaf out in March as usual. Watch the bark for cracks. Longitudinal “frost cracks” can callus over if not too deep. We are crossing our fingers on this one.

 

 

 

 

 

 

 

 

Shumard Red Oak and Texas Red Oak:   I am not too worried about these, other than the sudden drop in temperature from a warm winter, then a quick warmup which could influence frost cracks.  They will usually take the temperatures we had, and have the benefit of being deciduous.

Canby Oak: Although hardy to Zone 5, they did not have a chance to acclimate like their northern counterparts, and were still holding leaves when the freeze hit, so there may be some damage. Young trees have thin bark so watch for frost cracks. 

Chinquapin Oak: Also hardy to Zone 5, and since they are fully deciduous, I would expect these to come through pretty well.

Cedar Elm: Although these trees are prone to breakage due to narrow branching angles, they are very winter hardy here. (Zone 6) Prune broken branches at the appropriate place on the trunk to avoid future disease issues. 

Lacebark Elm: Again, a deciduous tree hardy to Zone 5. I expect most to recover well, unless they were stressed or very young.

Chinese Pistache: Hardy to Zone 6a and fully deciduous, we are expecting these to do pretty well, with some pruning likely needed after they leaf out.

 

Obviously, we did not cover all plant damage possibilities, but have tried to touch on ones that people are concerned about or that have been damaged in past hard freezes. Please don’t hesitate to contact the nursery with additional questions, but please realize we may not have the answers! We are all in this together, and will have to wait and see how our plants will recover.