At What Temperature Does Frost Occur On Plants

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Last Updated on December 15, 2022 by Griselda M.

One major thing gardeners are worried about is the frost effect on their plants. You need to understand and be aware of what temperature frost occurs on plants to protect your plants. Having an idea of the frost or freezing date in your zone can be quite helpful.

We will be enlightening you about what temperature frost occurs on plants. Also, we will give you some tips about what you can do to protect your vulnerable plant from frost damage.

Frost and What It Does to Plant

Frost is a bunch of minute ice crystals that settle and form on solid objects or surfaces. This happens when the temperature drops and gets cold.

Frost will settle on your plants and form ice crystals in your plant cells. This will, in turn, harm your plant making water unavailable to your plant tissues. It will also cause disorder in the movement of water across your plant cells.

Frost and What It Does to Plant - At What Temperature Does Frost Occur on Plants

Frost will injure the leaves of your plants making them look soaked. They will make your plant leaves look wrinkled and turn black or dark brown.

At What Temperature Does Frost Occur on Plants

The temperature at frost occurs on plants is 32 degrees Fahrenheit and below. However, in a few cases, frost can occur on plants a little above 32 degrees Fahrenheit.

  • Light freeze or a light frost refers to the temperature that drops a few degrees or exactly 32 degrees Fahrenheit for just a couple of hours or a night. Some rugged or hardy plants can survive this.
  • A hard freeze or a hard frost occurs when the temperature drops below 28 degrees Fahrenheit for a long period. Most plants may end up damaged with a hard freeze.

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Temperature That Causes Frost Damage in Plant

Various plants, experience frost damage at different temperatures. Here is a temperature table of when some vegetable plants get frost damage:


S/N Vegetable Plants Temperature (°F)
1 Spinach 30-32
2 Asparagus 30-31
3 Okra 29-30
4 Broccoli 29-30
5 Cabbage 26-28
6 Cucumbers 30-32
7 Carrots 28-30
8 Tomatoes 32-34
9 Sweet corn 32-33
10 Beans 31-32
11 Peas 28-30

Protecting Your Plants From Frost Damage

You need to devise some ways to protect your vulnerable plant from frost damage. Below are things you can do to protect your plants from frost:

  • Be enlightened about the weather forecast in your area especially when you observe the temperature will drop.
  • Protect your tender and vulnerable plants by covering them with plastic sheets, blankets, row covers, bedsheets, and so on. Take off the covering whenever the temperature rises so your plant can receive sunlight.
  • You can as well put an outdoor lamp of 100-watt to reduce frost damage and keep your plant warm in extreme cases.
  • Also, water the soil of your plant deeply and thoroughly. This way, the wet soil will conserve some heat and warm the root of your plant thereby protecting your plant from frost injury.


What is Plant Frost Cloth Made Of?

Frost cloth is made from spun synthetic plastic materials with the two most common being Polyester compounds in the PET Family (Coke bottle – look for the 1 in the recycle symbol) and Polypropylene.

There is some importance in the material you choose to buy for your area. The minimum temperatures in my area tend to be an absolute minimum of about 25°F on one or two days a year for a few hours. Polypropylene becomes brittle at these temperatures, reducing the working life of your frost cloth.

If you live in an area where you can expect colder temperatures more often, I would suggest buying a Polyester frost cloth – PET polymers can easily survive temperatures as low as -94°F (at which point you do not need to really worry about any green seedlings being alive). PET is in most cases a superior material, hence pay a little extra if you can and buy a Polyester/PET frost sheet.

What Plants Protect Frost?

There are a few plants that can help you protect an area against frost. This only really works in areas where temperatures do not go too low for too long. In other words, areas where temperatures would not be below freezing during the day. I live in such an area and people have devised many ways to protect plants against frost using natural methods.

Protecting sensitive plants with frost-resistant plants provides some thermal blasting. If you imagine a plant that has a certain amount of frost resistance such as Aloe ferox, it also is a plant that contains a lot of water. Water stores heat, so an aloe warms up during the day, and slowly cools down at night.

In some cases, these aloes can actually reduce frost around them a little bit. Crassula ovata can do the same, as does Portulacaria afra. In the natural environment where these plants grow, you will find that grassland adjacent to clumps of succulent plants will get frosted, but the succulent areas will not.

If temperatures drop too low for too long, succulents will have to get frosted, which can cause the growth shoots, or in some cases, the entire plant, to die.  Wrapping aloes with frost cloth also helps them to warm up more during the day, and they radiate this heat into the surroundings at night, reducing the risk of frost close to the aloes.

Trees such as Melaleuca bracteata can be planted in mild climates where frosts happen at night, but where temperatures do not often go below freezing. These trees can help to keep warm air close to the ground during colder patches, and have been used in many parts of the world for creating small frost-free patches.

How Do You Make a Frost Cover For Plants?

For small plants, the easiest way is just to cut a one-gallon PET water bottle or similar container to create a dome that you place over your plants. This is called a Cloche, and you can also buy these.

If you need to protect larger plants, you can either buy a cloche tunnel that can protect a vegetable or flower bed, or buy cloth to wrap around the plant

I have a friend who tries to grow avocado trees in an area that gets black frosts, and he wraps his trees with a frost blanket as detailed above, and also puts incandescent Christmas lights such as these around his tree. Incandescent lights generate some heat, unlike LED lights, hence if you do this, it is a good idea to buy incandescent lights (old-fashioned bulbs).

What Do You Do if a Plant is Damaged By Frost?

If a plant is frosted, you can often gently spray it with water before the sunlight hits its leaves – use a watering can, and this can slowly thaw the leaves and you will get a lot less damage. My Mom has brought most of her frost-sensitive crops through this way for 5 decades and swears by it. I have an irrigation sprinkler system that I set to run just before sunrise in colder times and I have had no serious frost damage since I have done this.

Which Plants Have Been Genetically Engineered to Become Frost Resistant?

Genetic engineering is a very expensive technology, and it takes years for a plant to make it from laboratory demonstrations, to field trials and through all the biosafety requirements of governments, states, and so on.

The result is that the majority of genetic engineering work focuses on staple crops, such as wheat, barley, and maize. These crops can cover the huge costs required to develop such plants and there are a few examples that have made it to market.

There is no profitable way that it would be viable to produce a genetically modified frost-tolerant garden shrub for example – the sales volumes of these plants would not cover the hundreds of millions of dollars required to get the plant from the lab to the field over 10 years.

Will My Plants Freeze Tonight?

This will depend on the temperature and the topography of your land. If the temperatures are predicted to be close to freezing in your area, and your plants are in hollows where cold air will accumulate – the chances are the answer is yes as these areas will tend to be a bit colder than the predictions.

If you are on top of a hill, your get wind at night and the temperatures are predicted to be close to freezing, probably not!

Does Netting Protect Plants From Frost?

Yes, it does. It helps retain heat in your plant so that it can avoid being frosted. This will not work in very very cold temperatures, but if the temperature briefly flirts with freezing you may get past it. I have found that with seedlings I prefer to use cloches, but with entire beds, netting cloches work and wrapping trees and aloes in cloth definitely helps them survive.

Final Note

Have in mind that frost won’t only hit during winter, frost can occur during fall or spring in some zones. This is why you need to take some precautions to avoid frost damage to your plant.


What temp is considered frost for plants?

Plants can tolerate a wide range of temperature ranges, but there are specific threshold temperatures that must be met before they will grow and flourish.

Frost is the most common type of plant damage that occurs at temperatures below 32 degrees Fahrenheit. Plants will grow normally in the low-temperature zone up to 32 degrees Fahrenheit, but below this temperature frost may occur on stems or leaves in cold climates.

Should you cover plants at 39 degrees?

Who should you cover your plants at 39 degrees? On a cold day, when moisture is scarce due to winter weather, they will be safe. However, if you live in a humid region and don't want your plants to die due to too much water and sunlight exposure, then this is not an option.

Is 40 degrees too cold for flowers?

In reality, when the temperature goes below 40 degrees F., there is a spike in plant metabolism and some plants go dormant until conditions are more favorable again.

How do I know if my plants have frost killed them?

When plants are exposed to frost, it can cause a lot of damage. The damage can range from browning leaves and dry out the plant to killing the plant completely. Knowing how to tell if your plants have frost killed them is important in order to avoid unnecessary waste of time and money.

The leaves will be brown and there will be lots of dead or dying leaves as well as stems. The plant will have a noticeable yellowing or browning color. If you spot these signs on your plants, they likely have been frost killed by frost.
For indoors plants, it is best to check the leaves for frost damage within a few days of a frost. To do this, you should use your hands to gently push down on the top of the leaves and feel for any raised areas or bumps.

For an outside plant, it is easier to see if the leaves are frosted. To do this, simply look at how much water you see coming out of where stems meet leaves. If you can see water dripping from where stems meet leaves then the plant has been damaged but if no water comes out then its fine.

Some plants will show symptoms of frost damage on their leaves quickly while others may not show their symptoms until they have been damaged by moisture on their roots.

What plants should I cover for frost?

Plants that can withstand frost are long-flowering plants that have tubers, bulbs, or rhizomes. These include various plants such as tulips, hyacinths, narcissus and many others.
Here is a list of some plants that should be covered by frost protection:

- Azaleas

- Calla Lilies

- Camellias

- Daffodils

- Magnolias - Rhododendrons

Can you wash frost off plants?

Frost is a natural phenomenon that happens during winter. It usually settles on plants because of low temperatures. Frost damages plants, which can be devastating to the overall health of the plant.

Some people think that if they spray water on the frosty leaves, they will wash off the frost and kill it. However, this is an incorrect practice and may even lead to more problems than it solves.
Frost is a type of ice that forms and accumulates on plants and shrubs during the cold winter months. More often than not, it's not just the leaves of plants that get frosted, but the flowers, stems, trunks or even the roots.

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