Ideal Temperature For Tomatoes & How to Protect from Extreme Temperatures?

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Quick Answer: Ideal Temperature Conditions For Growing Tomatoes

Tomatoes are warm-season plants that grow well when planted after the frost scare. They require a daytime temperature of 70-85oF and a night-time temperature of 59-68oF. They may withstand extreme temperatures only for short period. Beyond that, there may be poor fruit yield, pollen germination, and stunted growth. You may take a few precautionary measures and use resistant varieties to survive sub-optimal temperatures.

Are you planning to grow tomatoes and wondering about ideal temperature conditions? If yes, this guide will provide answers to all your queries.

Written using my 10+ years of experience growing tomatoes and advice from fellow gardeners this guide will surely be of great benefit.

Read on!

What Climate Conditions are Ideal for Tomatoes?

Tomatoes prefer warmer climates for their growth and development. Their tolerance to different temperatures depends on the cultivar.

Tomatoes are one of my favorite fruits in my garden. There are a plethora of varieties starting from heirloom to cherry in different colors and shapes.

The first step in knowing how to grow tomatoes well is understanding the ideal temperature in which they thrive.

I start early and have a plan to get the maximum yield from the plants. The tomatoes prefer warm weather like most of the fruits and vegetables.

Their tolerance to temperatures varies depending on the variety.

When To Plant Tomatoes?

You may start growing tomatoes indoors. Transplant the seedlings once the danger of frost has subsided, and soil temperature is warm.

Most tomatoes are warm-season plants and require three to four months of warm, dry weather. They may be planted after the danger of frost has subsided. It may be because the extreme cold or heat snaps may affect blossoming and subsequent fruit set.

Check out our detailed guides on the ideal time for planting tomatoes in various US states here>

You may check seed packets for the number of days for germination and maturity. Start growing the seeds indoors or greenhouse.

You may plant the seedlings after the ground warms to 60oF.

Make sure the soil is warmer during planting. Else, it may affect root development and plant growth.

Ideal Temperature Range For Growing Tomatoes

The ideal daytime temperatures for tomatoes are between 70-85oF. The preferable night-time temperature range is 59-68oF. They may withstand extreme weather conditions for a shorter period.

The ideal growing temperatures for tomato seedlings also vary depending on the stage of growth.

Guidelines on Temperature Range

They require temperatures between 58-60oF in the greenhouse or indoors to germinate. It also prevents the seedlings from being eaten by slugs or other creatures.

After the seedlings emerge, the ideal daytime temperature required for tomatoes is between 70 and 85oF and the night-time temperature range is 59 and 68oF.

A research paper suggested that the fruit set is optimal between 65oF-68oF. Tomato plants may withstand extreme weather conditions for a shorter period.

They may survive temperatures up to 33oF.  However, the extended period of exposure may affect the fruit yield and kill the plants.

Effect Of Extreme Temperatures on The Tomato

The tomato plants exposed to sub-optimal temperatures may have poor pollination, reduced fruit development rate, and lower fruit-set. It may be because the plants focus more on survival rather than producing fruits.

The tomato plants exposed to consistent cool nights (below 55oF) or hot days (above 90oF) and night spells (above 75oF) affect the fruit yield.

They focus primarily on surviving.

The effect of extreme temperatures are –

  • Lower leaf initiation rate
  • Low fruit development rate
  • Reduced fruit-set
  • Lower pollination 
  • Stunted growth

The plants exposed to freezing temperatures may cause the darkening of the leaf or stem tissues. They may start wilting and turning brown. It results in stunted and wiry plants.

Impact of Low Temperatures on Tomato Plants

Cool night-time temperatures may interfere with the ability of the plants to convert sunlight into sugars. It may cause catfacing or misshapen fruits.

They are also prone to damage due to chilling injury at temperatures between 32oF to 41oF.

It may cause stunted growth, wilting, surface pitting, and necrosis of foliage. It may also increase the susceptibility to disease.

Impact of High Temperatures on Tomato Plants

Consistently high temperatures affect the growth and development of tomato plants. It also disturbs fruit yield, development, and maturity of fruits.

If daytime temperatures are over 90oF for two or more days in a row, it may affect pollination. It may also lead to poor pollen germination.

Also, if the night temperatures stay above 85oF, fruits may not color properly and quit growing.

The University of Florida suggests the flowers must be pollinated within 50 hours. Otherwise, they may drop off.

Another issue I have noticed was exposure to high temperatures causes curling of tomato leaves.

It may be because the plant tries to reduce the transpiration of water.

Table: Effect of Temperature on Fruit Yield

Temperatures > 95FReduce fruit yield
Temperatures between 70-85FIdeal for fruit yield
Temperatures <55FMisshapen or catfaced fruits
Temperatures <50FPoor fruit yield

The extreme temperatures may stress the plants, resulting in poor fruit yield, stunted growth, and ultimately, the death of your plants.

How to Protect Tomato Plant from Extreme Temperatures?

Plant the tomatoes only after the scare of frost has subsided in spring. You may use raised beds, mulch,  heat mats, and cold frames according to the climatic conditions to thrive better.

1. Take Steps to Negate Extreme Temperatures

It is a pleasure to bite into ripened, homegrown tomatoes.

But, if you live in an area with unusual climate or weather conditions, you may follow a few measures and tips mentioned below to get juicy fruits.

  • Do not plant tomatoes until daytime temperatures are at least 75oF.
  • I prefer to use raised beds as they warm the soil faster than planting directly in the ground.
  • I cover my young plants with plastic, water-filled cloches.
  • Mulching when planting may raise soil temperatures and prevent soil drying.
  • You may extend the growing season with cold frames and heat mats.
  • Planting tomatoes on the south side in a cool climate.

Click on this video for a few tips on growing tomatoes in a hot climate:

2. Use Temperature Resistant Tomato Varieties

You may use temperature-resistant varieties if you live in an area with extreme climatic conditions. You may contact the local gardening store for more information on different varieties suitable for your area.

If you live in a place with an unusual climate, you may contact your local gardening stores. They may suggest a few heat or cold-tolerant varieties suitable for your area.

Best Heat Resistant Tomato Varieties

Several tomato varieties are available that are resistant to heat, humidity, and drought. Few examples are

  • Green Zebra– Heirloom, determinate, 78 days to maturity, green.
  • Sioux– Heirloom, semi-determinate, 78 days to maturity, red.
  • Big Beef– Hybrid, indeterminate, 73 days to mature, red.
  • Fourth of July– Hybrid, indeterminate, 49 days to mature, red/pink.
  • Super Fantastic– Hybrid, indeterminate, 70 days to mature, red.
  • Mountain Crest– Hybrid, indeterminate, 74 days to mature, red.

Best Cold Tolerant Tomato Varieties

The best cold-tolerant varieties are short to mid-season tomatoes. They may reach maturity in shorter days. Few cold-hardy tomatoes are

  • Celebrity– Hybrid, 70 days to mature, mid-season, bright red.
  • Orange pixie– Hybrid, determinate, yellow-orange cherry tomatoes, 52 days to maturity.
  • Bush Beefsteak– Heirloom, 65 days to harvest, determinate, mid-season, suitable for containers.
  • Glacier– Heirloom, early-maturing, potato leaf variety, suitable for container gardening.
  • Manitoba– Heirloom, 58 days to mature, meaty with tangy flavor, suitable for small spaces.
  • New Yorker– Heirloom, 63 days to mature, crack-resistant, perfect for home gardens.

FAQ’s

What happens to tomato plants if the night temperatures are too warm?

When the night temperatures are too warm, the pollen grains may burst. It will affect pollination, flowering, and finally, the fruit yield. So, tomato plants may not prefer very high night temperatures for an extended period.

Is 40oF too cold for tomatoes?

Yes. The tomatoes prefer night-time temperatures between 59oF and 68oF. 40oF may be too cold for tomatoes, and may affect fruit yield and inhibit pollen formation.

Summary

Hope this guide helped you understand the ideal temperature conditions for your tomato plant.

If you have any tips to share, do write to us with your suggestions.

Do share the article with your friends and family!