How to Treat Cold Damaged Houseplants?
What is the minimum amount of cold that a plant will survive? That depends, of course, on the hardiness of the plant as well as the climate. Under normal circumstances, many kinds of plants will be rapidly damaged or even killed when temperatures dip below freezing. However, by taking care of these plants promptly, many of these cold damaged plants can be rescued. Better still, a preventative measure like protecting plants from freezing cold frost is generally a good idea.
As diligent parents might do, overprotective gardeners might become alarmed when they notice frost on their plants. Though you may be tempted to fuss over them right away, it’s best to hold off on this for a few days until new growth appears, and then you can assess the damage correctly.
Assess the Damage
If your plants go through a light freeze, your leaves may become damaged or discolored. If this happens to your plants, have patience and wait for the damaged bits to dry on their own. The more severe the frost, the more likely it is to affect the plants’ roots and crowns. Therefore, there is a risk that the damage reaches the cellular level, which means it might permanently harm the tissue. Even though the plants may be able to recover with time, there’s still a chance they may not. Given this, we recommend that you check on them at least several months beforehand.
Plants that have sensitive foliage should be covered to protect them from the cold. If frost is expected, cover them with a plastic greenhouse cover, heavy sheets, or inside containers. Remove the covers from your plants in the morning. Placing the covers over your plants overnight will help to protect them.
Move your tropical plants inside. If you live in an area which gets sporadic cold snaps, you should bring your plants in or at least move them underneath a covered porch/deck. In cases when temperatures are expected to drop a lot, place the plants indoors in a garage or greenhouse.
Make sure your plants are hardy enough to withstand the fluctuations in temperature in your area. It’s even better to plant native plants since they have evolved to grow in your region and can withstand colder weather. Added warmth in the greenhouse can help your tropical plants adapt, so place them near a window if you can’t bear to give them up.
How Much Cold Will Kill a Plant?
You cannot tell how much cold the plant will withstand by just looking at the plant. Be sure to check the cold hardiness of the plant in question before leaving it outside in cold weather. The temperature of some plants’ leaves can be sub-freezing for months, while other plants can’t take temperatures below 50 F. (10 C.) for longer than a few hours.
What Happens to Cold Damaged Plants?
Most people are asking how much cold will kill a plant, whereas the real question should be how much freezing will kill a plant. Frost damage to plant tissue can have a negative impact on plants.
With the exception of very tender plants, light frosts usually don’t cause major damage, but hard frosts freeze water in plant cells, causing dehydration and damage to cell walls. When the sun emerges, cold injury is more likely to occur. As a result of damaged cell walls, plant leaves and stems defrost too quickly, causing them to die.
It is important to protect young trees, especially those with thin bark, from cold temperatures. Frost cracks develop if temperatures drop drastically through the night after the sun heats them during the day. However, they are often not visible until spring. If the cracks are not ragged or torn, however, they tend to heal themselves on their own.
Saving Frozen Plants
Water
Although it seems counterintuitive, the best thing you can do for your cold-shocked plants is to allow them to drink water throughout the day. This will allow them to recover from the trauma and the stress they endured. Put about an inch or so of water on your damaged plants. When plants experience a freeze, the moisture in the tissues is removed. In the morning, allow them to drink a glass of water that rehydrates them.
Fertilizer
Although you may be tempted to add a little fertilizer to your plants to help them recover, hold off. Doing so too early may encourage new growth before the cold weather has passed. It is best to wait until spring to begin application of fertilizer. As soon as danger of frost has passed, fertilizer can help speed up recovery.
Pruning
The temptation is also to remove damaged leaves and shoots from your plants, but pruning them may emphasize their problems even more. Wait until the weather gets warmer before removing the damaged parts of the plants (or, if you kept them inside in winter, about a month before cutting them off). You should assess the damage later in winter, if the plant is a woody variety. Simply scratch the bark and look at the color underneath. The plant is still alive, and will grow again if it has any water. If the leaf is not green, then it is still alive. For now, just clean off any dried leaves that fall from your plants.
If any of your tropical plants were frost-damaged, bring them inside into the house and either place them outside on a deck or porch (or put them in your garage). Do not place them too warm in a room as that will also cause shock. Leave them indoors, out of direct sunlight, and continue to water them as necessary, assessing any damage you see as you go. When plants are left outside in a container, they can use each other for warmth. If that’s not possible, make sure they are huddled together since they won’t lose their leaves.
If You Have Succulents, Handle Them With Care
A growing succulent or cactus will freeze if it has stored too much water in the stems and body. It is more likely to suffer cell damage as a result. It’s good to know that most of these plants are super hardy, so you can probably just tear off damaged foliage on them. After several days, examine the plants. If their interiors have turned mushy or black, they can probably be discarded. Nevertheless, if you notice new growth, you’re most likely going to be seeing them again the next year.
Protecting Plants from Cold and Frost
Although freezing plants is possible and causes freeze damage, the loss of tissue from freeze exposure or other damage can usually be prevented. Frost-prone plants can be protected with layers of sheets or sacks, particularly when temperatures are below freezing. When the sun returns the following morning, these should be removed. Additionally, potted plants should be moved to a sheltered location, preferably indoors.