Skip to Content

Can Tomato Plants Survive 40 Degree Weather

Tomatoes are one of the most popular summer garden plants. Fresh-picked tomatoes from the garden have a flavor that ones from the grocery store can’t match. Weather isn’t always consistent, and there can be cold nights during the summer and early fall. Can Tomato Plants Survive 40 Degree Weather?

Most tomato plants cannot survive 40 degree weather. Even though tomato plants can survive temperatures above freezing, they will struggle when temperatures decrease to 40 degrees.

Tomato plants prefer warm temperatures, sunshine, and rich, well-drained soil. So, what can we do when there’s a cold snap during the growing season? What about at the end of the season when fall temperatures become cool? Read on to discover how to help your tomatoes survive 40-degree weather and what to do if you weren’t prepared.

What is the coldest temperature tomato plants can handle?

Tomato plants can withstand temperatures just above freezing, as low as 33 degrees, but this doesn’t mean they will thrive or produce tomatoes.

Consistent temps below 55 can produce “catfaced” tomatoes – misshapen fruit with brown scarring, holes, or cracks.

In temperatures below 50, the plants will flower but not produce fruit, and tomatoes may drop off the vine. Green tomatoes on the plant will likely not ripen with prolonged exposure to these temperatures.

Temps between 32 and 41 degrees will stunt growth, and the leaves will wilt or dieback.

The ideal growing temperature range for tomatoes is 65-85 degrees F during the day and 59-68 degrees overnight. A minimum of six hours of sunlight is needed, and eight hours is ideal.

Gardeners plant tomatoes when the danger of frost is over, and night temperatures will regularly be above 55. Protection is recommended if it is below 50 degrees.

How do you keep tomatoes warm at night?

If the plants are in pots, you can bring them indoors for the night. If the plants are in the ground, you will need to keep them warm enough in the garden overnight.

To increase the surrounding temperature of a tomato plant, use covers. They vary in construction, but most can increase the temperature by 3-5 degrees. So, with temperatures between 27 and 32 degrees, covers will keep the plants above freezing temps.

Seedlings and Young Plants

These are the most susceptible to cold due to their small size, but you can cover each plant individually to protect it from low temperatures or frost.

You can use one of the following:

  • Garden cloche
  • Plastic jug with the top cut off
  • Bucket
  • Cardboard box

You can also use any of the types of covers for mature plants.

Mature Tomato Plants

Because these are bigger and taller, you will need other methods.

Options are:

  • Cloth row covers
  • Frost blankets
  • Mylar thermal blanket
  • Clear plastic (must not touch any part of the plant)
  • Bedsheets
  • Large cardboard boxes
  • Tarps on top of another cover to increase the insulation

To keep the cover from touching the plant, you can use stakes around a group of plants and drape the material over the stakes. Or, if the tomato plant is in a cage, use that to hold up the material. Make sure the covering goes to the ground and use rocks or bricks to keep it in place.

You can add a light under the cover to add an extra bit of heat, such as an outdoor light or a string of incandescent Christmas lights on the ground around the plant. LED bulbs won’t get hot, so they’re not helpful for this.

Adding mulch around tomato plants will help keep the soil temperature warm.

Water the plants in the afternoon before a cold night since hydrated plants tolerate cooler temps better than dry ones.

Be sure to remove the covering in the morning when temps reach above 50 degrees so the plants do not overheat.

Can tomato plants recover from frost damage?

If you check the plant in the early morning and it’s not entirely frozen, you can spray it with water, which will melt the frost.

If the plant has fallen, it can’t be saved. Check the stem under the bottom set of leaves. If this is soft or discolored, the plant won’t survive.

If these conditions don’t appear, then look at the rest of the plant for these symptoms of frost damage:

  • Tan or brown spots on leaves or black leaves
  • Yellow or purple stems
  • Soft stems

If the only damage is to the outer edges of the leaves, then the plant should be fine.

If the main stem is healthy, you can prune off the affected parts of the plant. Remove the damaged leaves and any soft stems by pruning with garden shears. If any tomatoes are entirely frozen and have not been thawed, you can put them in your freezer. You can salvage a partially frozen tomato by cutting off the damaged part if it’s not extensive.

Prevent additional frost damage by using the covering options listed above.

What do you do with tomato plants at the end of the season?

68-77 degrees is the ideal temperature range for tomatoes to ripen. When the growing season is ending and temps are getting cooler, there are ways to save and ripen the tomatoes that aren’t completely red or are still green.

Pick the almost-ripe tomatoes before night temperatures get so low that they may develop cracks or brown scars (below 55) or may not ripen at all (below 50). These will be almost red or very light green.

As frost predictions appear in the weather forecast, you may want to pick the rest of the tomatoes on the plants.

If there has been a light frost, pick all the tomatoes.

You can ripen the tomatoes using one of these methods:

  • Put it on a sunny windowsill. This works best for tomatoes that have some red color.
  • Place them in a brown paper bag with an apple, which releases ethylene gas that promotes ripening.
  • Store them in a dark place. Either lay them in a single layer or wrap them individually in newspaper. It will take about two weeks for the tomatoes to become ripe.

For all these methods, check on them frequently for rotting.

You can also find delicious recipes for fried green tomatoes.

Final Thoughts

Home-grown tomatoes are one of the most delicious crops in a garden. When you live in a climate where the weather can become cold during the growing season, it’s worth knowing how to prevent problems with your tomatoes from falling temperatures.

As you’ve read, 40 degrees Fahrenheit is too cold for tomato plants to produce fruit. Using one or more of the methods described, you can help your plants get through a cold snap and continue to grow and produce red, juicy tomatoes.

There are varieties of tomatoes that are hardier than others. Do some research before buying seeds or seedlings to determine which ones are best for where you live. Enjoy growing tomatoes in your garden and feel more confident now that you know the ways to prevent cold or frost damage to them.