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Tips For Saving Cold Damaged Plants

Tips For Saving Cold Damaged Plants


By: Nikki Tilley, Author of The Bulb-o-licious Garden

How much cold will kill a plant? Not much, although this is usually dependent on the hardiness of the plant as well as the climate. Typically, temperatures falling below freezing will quickly damage or even kill many types of plants. However, with prompt care, many of these cold damaged plants can be rescued. Better still, protecting plants from freezing cold and frost before damage occurs is generally a good idea.

How Much Cold Will Kill a Plant?

How much cold will kill a plant is not an easy question to answer. Be sure to look up the cold hardiness for the plant in question before leaving the plant outside. Some plants can survive sub-freezing temperatures for months while others cannot take temperatures below 50 F. (10 C.) for more than a few hours.

What Happens to Cold Damaged Plants?

While many people ask how much cold will kill a plant, the real question should be how much freezing will kill a plant. Freeze damage to plant tissue can be detrimental to plants. Light frost typically doesn’t cause major damage, with exception to very tender plants, but hard frost freezes water in plant cells, causing dehydration and damage to cell walls. Cold injury is more likely to occur as the sun comes up. As a result of these damaged cell walls, the plant defrosts too quickly, killing leaves and stems.

Young trees or those with thin bark can also be affected by cold temperatures. While not always visible until spring, frost crack results from sudden drops in nighttime temperature following the daytime heating from the sun. Unless these cracks are ragged or torn, however, they usually heal themselves.

Saving Frozen Plants

In less severe cases, cold damaged plants can be saved. Frost crack damage in trees that require repair can usually be saved by carefully cutting away the torn or loose bark. Smoothing out the edges with a knife will allow the tree to form a callous on its own. To help minimize frost damage to other woody plants, lightly mist foliage before the sun hits them. Likewise, potted plants can be moved to another location away from direct sunlight.

Unless damaged plants are moved indoors or another sheltered area, do not attempt to prune damaged leaves or stems. This actually offers additional protection should another cold spell occur. Instead, wait until spring to cut away the damaged areas. Prune dead stems all the way back. Live stems, however, need only the damaged areas cut back, as these will eventually regrow once warm temperatures return. For soft-stemmed plants suffering from cold injury, immediate pruning may be necessary, as their stems are more prone to rotting. Cold damaged plants can be watered and given a boost of liquid fertilizer to help aid in their recovery.

Protecting Plants from Cold and Frost

While saving frozen plants is possible, freeze damage to plant tissue and other cold injuries can often be prevented. When frost or freezing conditions are expected, you can protect tender plants by covering them with sheets or burlap sacks. These should be removed once the sun returns the following morning. Also, potted plants should be moved to a sheltered location, preferably indoors.

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Most houseplants come from subtropical or tropical climates where temperatures stay fairly stable year-round, although some hail from temperate areas and will tolerate some cold. Species such as the corn plant (Dracaena fragrans) grow outdoors in frost-free climates of U.S. Department of Agriculture plant hardiness zones 10 through 12 and will suffer cold damage at temperatures below 50 degrees Fahrenheit, while Dutchman’s pipe (Aristolochia macrophylla) will survive outdoors in USDA zones 4 through 8 and can tolerate below-freezing temperatures.

In most cases, daytime temperatures between 65 and 75 F and nighttime temperatures above 55 F will provide the right conditions for growth with minimal risk of damage.


The best prescription for cold weather stunned plants is to "wait and see." Once the threat of frost is past and new growth starts to appear, you may trim away the dried, dead foliage. Do this sparingly, resisting the urge to prune heavily. In the case of delicate perennials, go ahead and remove decayed leaves and branches. If you can find it within you to leave them alone, however, the dead parts will eventually fall off on their own. Do water your plants after a heavy frost. They will need water to help them push forward to new growth.

In the case of container plants or potted plants, such as tropicals, which have been left outside too long, the only remedy is to bring them inside as soon as possible. Do not put them directly into a very warm room. Bring them into the garage or on a sun porch. You don't want to shock them further with intense cold followed by too much heat. Most often, with water, nutrients and warmth in the right quantities, the plant will snap back. The dead parts will fall off and new foliage will eventually appear. If you leave container plants outside in the winter, group the pots together. This will help them retain vital warmth.


Protecting plants

The ever-increasing number of tender plants on offer may not withstand sustained cold without some form of protection. How you protect your plants from the effects of cold depends on the type of plants and the situation they are growing in.

  • Plants that are trained against walls or tender plants growing in the open ground can be protected with simple, fleece-covered frames. Alternatively, sandwich a layer of bracken leaves or straw between two large sections of chicken wire and use this to cover plants during frosty evenings. Tender bulbs, corms and tender, herbaceous plants (that die back) should be covered with a thick mulch of manure, straw or old leaves to prevent the soil from freezing. In the spring, new shoots can be protected with a loose layer of straw or a bell-cloche.
  • Evergreen plants will benefit from a thick layer of mulch around their bases to keep the soil frost-free. This will allow them to take up moisture during periods of cold weather and stop them from becoming dehydrated.
  • Tender plants should be grown in pots so that they can be moved inside during bad weather. Take cuttings of those that cannot be grown in pots and overwinter these in a warm greenhouse, ready for planting in spring.
  • Protect the crowns of tree ferns and insulate their trunks by wrapping them in layers of fleece or hessian stuffed with straw. Cordylines and palms should be treated similarly, by tying their leaves into bunches, to protect their crowns.
  • Protect low-growing plants from wet weather by covering them with a sheet of glass or a cloche and surrounding them with a layer of gravel or grit, to ensure swift drainage.
  • Choose outdoor containers that are frost-proof to prevent them cracking. Lift pots and containers into a shed or greenhouse for protection. Those that can't be moved should be placed on 'pot feet' to prevent waterlogging. Using a light, free-draining compost with added perlite will also help with this. Insulate them with a layer of bubble wrap or hessian to prevent them freezing and cracking and ensure plant rootballs stay healthy.


How to Spot Cold Weather Damage on Your Plants

Don’t give up hope on them just yet! We have a list of tips and ideas to guide you through taking care of those plants that have been damaged by the cold snap we’ve experienced. Typically, temperatures falling below freezing will quickly damage or even kill many types of plants. However, with prompt care, many of these cold damaged plants can be rescued.

Here in the Midlands, the January cold snap, especially following the warm November and December have affected plants that are generally cold hardy.

Take a walk through your yard and look for these signs on your camellias, tea olives, hollies, and podocarpus:

  • If leaves that are typically green in the winter have turned brown, resist the temptation to “fix” them. Don’t do anything right now.
  • Wait until the weather warms up and then fertilize after April 1 with a general tree and shrub fertilizer.
  • Wait until after new growth appears to prune away dead branches.
  • Camellia buds may drop without opening into full flowers. There is nothing you can do about that. Next year protect your camellias with a blanket and Christmas tree lights if you want to preserve the buds during a hard freeze.

Sometimes plants such as azaleas, pittosporum, hollies, gardenias, and mimosa trees won’t make their damage seen until the heat kicks in about June.

  • If you see branches beginning to yellow and die out this summer, look closely at the bark on the dying branches. If you see that the bark has split, this is due to the sap freezing in January.
  • When the plant tries to function in the summer, it can’t get enough water and nutrients up its stems, so it dies back.
  • If the affected areas are just some of the limbs, you can cut out the dead material and let the plant recover.
  • If the primary trunk is affected, the plant may not survive.

Plants that are rated Zone 8 & higher such as lomandra breeze grass, oleander, bottle brush, lantana, and angel trumpets may have been severely damaged during the January freeze.

  • Fertilize with a general tree and shrub fertilizer after April 1.
  • Wait until the weather warms up and look for new growth pushing out. If you get new growth, the plant survived.
  • Cut back dead plant material and wait for the plant to recover through the summer.
  • If you don’t see new growth by June, dig it up, throw it away and plant a new one.

Sago Palms

  • If the cold got to your Zone 8+ Sago Palms, they may look particularly dead and unattractive right now. Don’t do anything.
  • Fertilize with a palm tree fertilizer after April 1. We recommend Carl Pool Palm Food. Or if you have had problems with scale on your Palms in the past, use Fertilome Palm Tree Food with Systemic Insecticide.
  • New growth will appear out of the center of the palm in late May early June.
  • Wait until after the new growth appears before you cut off the brown fronds.

How much cold will kill a plant is not an easy question to answer. Be sure to look up the cold hardiness for the plant in question before leaving the plant outside. Some plants can survive sub-freezing temperatures for months while others cannot take temperatures below 50 F. (10 C.) for more than a few hours.

Here in the Midlands, we are rated zone 8a. The average extreme minimum temperature for zone 8a is 10-15 degrees. Coastal SC is rated zone 8b. The average extreme minimum temperature for zone 8b is 15-20 degrees. If a plant is rated hardy for Zone 8-10, it should survive temperatures that fall as low as 10 degrees. However, we have found that some zone 8 plants are hardy to zone 8b but less so for 8a. In other words, they will survive 15-20 degree temps, but not less than 15-degree temps. Also, we have found that a plant might survive one night of 14-degree temp, but several nights in a row will do it in. Also, remember that if a plant is rated hardy for zones 8-10, it likes warmer weather since zone 10 is South Florida. Zone 8 is its northernmost border of survivability. So, a zone 8-10 plant would be potentially more susceptible to extreme cold than would a zone 7-9 plant.

While saving frozen plants is possible, freeze damage to plant tissue and other cold injuries can often be prevented. When frost or freezing conditions are expected, you can protect tender plants by covering them with sheets, burlap sacks, or “frost cloth.” These should be removed once the sun returns the following morning. It’s vital as a gardener you watch the weather forecast and protect your plants when needed.

Here at Wingard’s Market, we specialize in providing outstanding customer service, offering professional gardening advice, and answers to your everyday gardening questions. Stop by and visit our Beautiful Gift Shoppe and Fresh Produce Market while you stroll under century-old pecan trees. It’s truly a Garden Wonderland!

Located at 1403 North Lake Drive in Lexington, SC. Call us at (803) 359-9091