What Happens to a Plant If the Temperature is Too Low?

Plants or humans – both need care, attention, and favorable conditions to thrive. Despite having a green thumb, one must always remember that plants are not living indoors by choice. Nature and gardening grow on us due to our ancestral memory. Our innate connection to our natural habitat of the past often makes us coax exotic tropical specimens to thrive in our homes. However, without replicating the plant’s natural growing conditions, we’d be only doing a disservice to our green friend.

Read this post to find out what happens to a plant if the temperature is too low!

What Happens to a Plant If the Temperature is Too Low
Frosted stinging-nettles on a cold morning

Temperature is one of the most important environmental factors that determine plant growth. It supports photosynthesis and respiration in plants. Tropical or temperate, each plant falls under a specific temperature range where it grows best. The environmental temperature also determines the plant’s hardiness or its ability to withstand the average minimum temperature without damage.

That said, unexpected drops in temperature cause the plants to wilt or die. The crops usually have different levels of hardiness, but if the temperature is too low for a plant, it decreases the enzyme activity and causes changes in the fluidity of cellular membranes.

Let’s dig deeper into the effect of cold temperatures on plants and how to protect them from cold weather shock!

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Effects of Low Temperature on Plants

Low temperatures aren’t completely bad for all plants. Many plants often bloom out of season and many others don’t go through enough chill time. Regardless, the fruit still turns out to be incredibly sweet. On the other hand, cold weather shock can be damaging to most plants.

Therefore, it is important for you to know the effects of cold weather on your plants and their hardiness. Typically, there are two types of injuries that a plant can suffer from as a result of low temperature, frost injuries, and chill injuries.

A plant can suffer from frost or freezing injuries at or below freezing temperature, which is 32 degrees Fahrenheit or 0 degrees Celsius. These injuries usually occur when an air mass with a below freezing point temperature moves in and displaces the warmer air of a region. This causes the temperature of the plant to drop low enough for ice crystals to form inside the plant cells.

The second type is chilling injuries that occur above the freezing point. Tropical and subtropical plants are more at risk of such cold weather injuries. The plants suffering from chilling injuries appear purple or reddish and sometimes wilted as well. This kind of injury is easily detectable and also causes blooming delay and hampers the growth of the plant.

Understanding a Plant’s Response to Low Temperature

There are various different factors that determine your plant’s reaction to cold temperature – your plant’s age, specie, water content and stage of growth, to name a few.

The types of plants that are likely more susceptible to cold weather shock are young, actively growing, flowering, and dehydrated plants. If you prune or fertilize your plant heavily in late summer or fall, it also puts your plant more at risk.

Similarly, winter hardy plants also require winter acclimation. This means that your plant must only experience lowering temperatures in full hardiness and acclimation. If a plant is exposed to a hard freeze without prior cold temperatures to harden off, the plant tissue is likely to more long-term damage. Your plant is likely to suffer greater damage if:

  • The temperature drop was fast.
  • The temperature was extremely low.
  • The temperature stayed low for a long time.

Needless to say, a plant exposed to 10 degrees for ten minutes is likely to take less damage than a plant exposed to 20 degrees for two hours.

Apart from temperature, there are certain periods of the year that put plants more at risk to cold weather shock. These include early fall, the period before a plant has acclimatized or during very cold temperatures after a couple of days of warm winter.

So, if the temperatures have been close to average for a few weeks and then suddenly drop to very cold temperatures, your plant is likely to experience frost damage.

Sometimes, the frost damage can also occur in late spring. This is because the rising temperature will allow growth and blooming, but new growth might not be as hardy as the old plant.

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Common Symptoms of Cold Weather Shocked Plants

More often than not, the symptoms of frost damage are easily detectable and visible. So, whether you want to make sure that you took in your plant on time or if your flower garden has fallen prey to the cold temperature, knowing common symptoms might help.

These symptoms will serve as your guideline to repair the loss of cold weather to your plants.

The Superficial Effects

Most perennial flowers and plants have a similar response to temperature drops. First, when the temperature begins to drop in the fall, they either slow down their growth and flowering or stop them altogether.

By the time of the first frost, they are already through their blooming period. However, sometimes a sudden drop in temperature catches them midway.

When the temperature falls below freezing point, the water vapors condense and freeze on the ground. Next, the cold wind hits the leaves and freezes the water inside the leaves.

The leaves of a plant have square-shaped plant cells arranged one after another. These cells have rigid outer walls while the inside is filled with water and cell structures. The external cold causes the water inside the cell wall to freeze which results in damage to the cell as well as to the plant.

In order to observe the common symptoms of cold weather shock to a plant, you should first make sure that the external temperature is cold enough to cause the shock. If your plant has been exposed to temperatures below the favorable range, observe the following two superficial effects on the plant:

Drooping Leaves

The first symptom that you will notice is that the leaves of the plant are curling or drooping. The curling signifies cell damage in the leaves. When the cells are damaged by low temperatures, they lose their rigidity, causing the leaves to droop.

Discoloration on the Leaves

The next common symptom is the discoloration of the leaves. You will notice white, yellow, or red marks near the veins in the leaves. These spots signify dead cells, damaged by the frost. Sometimes, not all cells are damaged by the frost.

So, you might notice certain areas that were damaged by the cold while other leaves might be fine. The leaves with damaged cells and discoloration might eventually die and fall off the plant.

Signs plants are too cold
Close up Image of Red Frosted Flower

The Internal Effects

Apart from superficial damage to the plants, cold temperatures also effect the plant internally. A few of the internal damages are as under:

Plant Cell Damage

As the external temperature drops, the water inside the plant cell freezes, causing the expansion and damaging of the plant on the inside. The damage done in cold weather might also make the plant wilt after the temperature rises up again.

Frost damage is worse in younger plants as these plants have not grown in strength and structure to withstand the expansion of cell tissues.

Desiccation

Cold temperatures can also freeze the plant externally, including the surround soil. This leads to desiccation as the frost interferes with the plant’s water supply.

Decrease in Enzyme Activity

Temperature below the favorable range can decrease the enzyme activity in plants, causing a disruption in the nutrient intake. In normal conditions, plants secrete enzymes to break down important nutrients that they obtain from the soil. A loss of nutrient intake can stunt growth and the plant might eventually wilt.

Changes in the Fluidity of Cellular Membranes

Cellular membranes are an important part of plant structure. They are responsible for ensuring that plant cells respond to slight changes in the environment. They are also incremental in the plant’s growth. But cold temperatures change the fluidity of cellular membranes, causing damage to the water flow through the plant cells.

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How to Control the Frost Damage and Protect Plants

Any plant that experiences the shock of cold season arriving early or suddenly might be vulnerable over the coming weeks. The key to protection against frost damage is prevention.

For any type of plant and environment, constant prevention can ensure healthy growth and development. Here are a few key practices that every plant owner and gardener should be aware of to help the plant survive through the cold weather.

Protect from Early Morning Sunshine

If you have ever frozen a fruit in the freezer overnight and then left it out in a warm environment for a few hours, you probably know the damage it can do. Similarly, cold weather damage can be a cause of a plant defrosting rapidly after a cold night. This can result in the drooping of leaves or wilting of the plant.

The first preventive measure that you can take against frost damage is to avoid positioning the plants where they would be exposed to early morning sunshine. So, move your plants from the east facing areas of your gardens or windows.

Check Water Temperature

In order to protect your plants from cold temperatures, check the temperature of your water at the end of the hose. Whether the water supply comes from a well or city water, check the average temperature at 7:00 a.m. and 3:00 p.m. after running the water for 5 minutes.

In cold weather, it is best to water the plants early in the morning before the sun warms up the plants. Apart from protecting the plant from chilling injuries, this would also reduce the risk of other plant diseases.

Use Cold Weather Fertilizer

You do not have control over the weather, nor can you move all plants indoors if it is a garden you are trying to protect from frost damage. Luckily, there is still a way to protect your plants from the cold damages. You can use a cold weather fertilizer to stimulate root growth despite low temperatures.

Harden Off Plants Before the Cold Season

Cold temperatures can cause long-term damages to plants, especially the younger ones. Therefore, to make them withstand the cold weather, it is important to give them the right protection as soon as you plant them. An important step in this early protection is to harden off the plants before the cold season.

As the young plant starts growing, take it from its indoor setting and gradually expose it to the cold environment outside. This will build its tolerance to naturally changing temperatures. That said, you must also choose hardy and native plants that can grow in the given environment.

Frost Prevention by Water

Many gardeners use a common practice of spraying water on plants to protect them from frost damage. This practice prevents ice from penetrating the leaves and fruit tissue. However, this trick only works if the water is sprayed continuously. If you stop spraying water, the temperature drops quickly below freezing, exposing the plant to frost damage.

It is also important to remember that this type of protection only works for plants with thick cuticle leaves and thick fruits. It has not been found to be very successful for perennials or woody plants. Since the rapid drop of temperature across the leaf is also quick, the frost damage will be long-term if you stop spraying water and leave the plant on its own.

Use Plant Blankets

Even better than the water spraying technique is using plant blankets. You can find good quality frost cloths to slow down the rate of cooling. The coverage will keep the temperature as high as possible so that the plant does not suffer from frost damage due to low temperatures.

The only downside of this protection is that if you have a lot of plants to protect, this method might be on the high-end side.

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What to Do If a Plant Is Frost Damaged?

If your plant had exposure to cold weather, the first thing to do is not give up on it too soon. The branches and some leaves might appear damaged, but sometimes they recover when spring comes around. Hence, a plant injured by the cold might need both spring and summer to revive and thrive.

Here’s what to do if cold temperatures have taken a toll on your plant:

Water

First things first, check the soil around your plant for any signs of dehydration. Often, the soil dries out or gets frozen due to the cold. If that is the case, water the plant to defrost the soil and provide your plant with the needed moisture. Even injured plants need sufficient water to revive.

Pruning

Another important thing to remember is not to prune plants right after the cold damage. The damaged foliage might look bad, but it will provide protection to the healthy part of the plant from further cold injury. When spring comes, assess the damage by scraping the bark slightly.

The frost damaged wood will appear black or brown under the bark. Wait a little more until the plant begins to sprout new growth before pruning.

Some plants that are damaged by the cold might collapse. In that case, cut off the dead part of the plant to prevent bacterial problems and decay. That said, just because a branch has dead leaves, it does not mean the branch itself is dead.

Similarly, the grass in your lawn might turn brown in winter. But there is no need to fret over it as it is a normal phase of winter dormancy. The lush green grass will come back around in spring season.  

Bring Your Potted Plants Indoors

If low temperatures have damaged any of your plants, bring them indoors and place them in an enclosed space, such as a garage. It is also important not to place them in a room that is too warm as that would also cause temperature shock.

So, place them indoors, away from direct sunlight, and continue to water them as per their needs. Take out some time daily to assess any further damage they have gone through. You will notice that the dead parts of the plants will fall off over time and gradually your plant will recover with appropriate care. 

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Conclusion

Whether you need some plants to deck out your room or just want to add some more collection to your garden, always remember that each plant has its own temperature limits. The key to adequate plant care is to know what happens to a plant if the temperature is too low or too high. A significant amount of research suggests that just having plants around can help you breathe happier and improve your mood. So, regardless of the environmental conditions around you, you can always find some plants to add years to your life and life to your years.