Tomato plants are a staple in most backyard vegetable gardens. This is hardly surprising, given that they are so popular worldwide. From cherry to beefsteak, tomatoes come in a variety of shapes and sizes.
For tomato plants to thrive, they require sunny locations, rich soil, and warm temperatures. They are not hardy in cooler regions and can be endangered by dipping temperatures and frost.
To safeguard your tomato plants, you must know how much cold they can withstand.
How cold is too cold for tomato plants?
Tomato plants can withstand temperatures above freezing (32°F). But if the temperature drops below freezing, the cold will likely kill your tomato plants.
Temperatures between 60°F and 85°F during the day are ideal for growing tomatoes.
If you’re going to put in the effort to grow tomatoes, you should first read our in-depth guide on how much cold the plants can tolerate and how to protect them.
Tomatoes and Cold Temperatures in a Nutshell
|Below 32°F||Your plants and their fruits will be badly damaged, if not killed, even by short-term exposure.|
|33°F – 40°F||Long-term exposure can cause the leaves to wilt and the plant to stop growing.|
41°F – 55°F
|When plants are exposed for a long time to chilly temperatures, they may grow incorrectly, lose their flowers, make less pollen, and produce fruits that don’t taste as good.|
What Temperature Is Best for Tomato Plants?
The first step in being a successful tomato grower is gaining a grasp of the environmental conditions, both indoors and outdoors, in which tomatoes thrive.
Temperatures during the daytime that range from 60°F to 85°F are ideal for tomato growing.
When it comes to the temperature at night, tomatoes like it a bit cooler than during the day. Temperatures between 55°F and 60°F at night are preferable.
Several temperatures are preferred by tomato plants during various stages of development.
Stage 1: Germination
Temperatures in the soil between 70°F and 80°F should always be maintained for optimal germination of tomato seeds.
Stage 2: Seedlings
Temperatures in the range of approximately 65°F are ideal for the growth of tomato seedlings shortly after germination and up until they have two to three new leaves.
Stage 3: Grown Plants
Tomato plants, once transplanted/planted outdoors, prefer warm temperatures.
If you want your tomato plants to be able to stay the night outside, the temperature needs to be higher than 55°F. This will allow them to thrive.
Your plant will suffer in colder temperatures, and its growth will be slowed. In the end, with the lack of suitable growth conditions, tomato plants will either provide poor fruit harvests or die.
How Do Tomato Plants Suffer When the Temperature Is Too Low?
Pollen cannot form if the temperature throughout the night dips to less than 55°F.
What’s more, if it gets too cold at night, the petals of the flowers might not even open, which could stop the pollination process.
When Blossoms Fall
In the spring, blossom drop may occur if daytime temperatures are high but nightly temperatures are below 55°F.
The Process of Photosynthesis
Temperatures that drop throughout the night might also disrupt the photosynthesis process during the day. If the plants produce less nourishment, then their development slows down.
Plants that grow in temperatures below 65°F during the day and below 60°F at night are more susceptible to infection by various diseases.
For instance, catfacing disorder tends to happen when the weather interferes with the process of pollination and fruit growth.
Catfacing is a defect that can appear on fruits; it can happen to unripe and ripe fruit, leaving scars of varied sizes.
Fruits Drop Off
In the event that the temperature drops below 50°F, tomatoes that are still on the vine typically drop off.
What Can I Do to Protect My Tomato Plants Against Cold Nights?
It’s not easy to save tomato plants from freezing temperatures.
Even in the best-case scenario, a cold snap can leave unattractive scars on the fruit and reduce the yield of tomatoes. In the worst case, the freezing weather could kill all your tomato plants in one night.
Because of this, you should know how to help your plants survive the cold.
While a garden cloche or row cover will not protect your plants from prolonged freezing weather, they are an excellent way to reduce the damage caused by a short cold snap.
Remember that the temperature under a cloche or row cover might quickly become too high for plants if the temperature outside rises.
Lifting plant covers at the right time is important to protect crops from heat damage.
This should be done first thing in the morning or immediately if the weather outside is changing.
A garden cloche is a cover made of either plastic or glass, placed over plants to shield them from the cold.
When the cold weather is on its way, it is best to protect plants by covering them up after dusk and then removing the cloche in the morning the following day.
The temperature inside a cloche will likely be 2 to 5 degrees higher than the temperature outside. This should be enough to shield a plant from a late or early frost.
Moreover, a cloche can be used to shelter fragile plants from wind and rain.
It is best to use a garden cloche when the tomato plants are still young and before they become too large to fit underneath.
Using any large container as a cloche in the garden is an inexpensive alternative to purchasing a specialized cloche.
You may use anything from a bucket or plastic planter to an upside-down trash can to cover the plant.
You could also cut the bottoms off big water bottles and use them as cloches for your garden.
Using a thick fabric row cover is another method to prevent the frost from hurting your tomatoes.
On the nights when the temperature falls between 28°F and 35°F, row coverings will protect your crops from damage.
They are not ideal, and there is still a high probability that you will lose your tomato plants if the temperature drops below 30°F.
Still, using a fabric row cover to keep your plants safe during the first few cold nights of the season should be enough to keep your plants safe.
Signs of Frost Damage
Cold damage can happen to your tomato plants if you have recently experienced a string of especially frigid days.
The main signs of frost damage are wilted and deformed fruits and leaves that have changed color.
Young plant leaves that are harmed by the cold will develop an olive green color and a shade of purple in their appearance.
When a plant reaches maturity, the leaves may wilt and turn dark.
The Best Time to Plant Tomatoes
There is no straight answer if you want to know when to plant tomato seedlings outside. Because the ideal moment to plant tomatoes varies greatly depending on where you live, there is no general right time.
You may, however, follow some rules of thumb that will assist you in picking the most advantageous timing.
When Should You Plant Tomato Seedlings Outside?
Tomatoes are warm-season plants, so that’s the first thing to remember in deciding when to plant them.
Many of us just starting gardening make the mistake of planting tomatoes too early in the season.
Also, keep in mind that tomatoes won’t grow in temperatures below 50°F.
Signs of Planting Season
Tomatoes should be planted when the average low temperature for a week is at least 50°F. For tomato plants to produce fruit, the night air temperature must be at least 55°F.
So, if you plant tomato plants when the nighttime temperature is at least 50°F, the plants themselves will have enough time to grow before producing fruit.
The soil temperature is another indicator that might determine the optimal time to plant tomatoes. When the soil temperature reaches 60°F, it’s time to plant tomatoes.
Of course, a soil thermometer can be used to verify the temperature of the soil, but it is not essential for the job.
Sticking a finger into the soil will tell you if it’s ready for tomato plants.
If it feels uncomfortably cold after putting your finger in the soil for a couple of minutes, you shouldn’t plant tomatoes just yet.
When Is It Too Late to Plant Tomatoes?
While knowing when to plant tomatoes is helpful, many of us also wonder how late we can plant them and still get a decent harvest.
How late can tomatoes still be planted?
The best way to answer this question is to count the days until harvest. The answer may change depending on what kind of tomato variety you have.
Typically, the number of days before harvest is printed on the tag of the tomato plant you purchase.
Then, you should check when the first frost typically occurs in your location.
Tomatoes can still be planted if the time until they reach maturity is less than when the first frost is expected.
The average time for tomatoes to fully mature is about 100 days. Yet, some varieties can be picked in as little as 50–60 days.
So if the season is in full swing and you’re still thinking about your tomatoes, find a variety with a short harvest period.
To sum up, growing tomatoes is a great hobby that may provide you with a bumper crop of healthy, delicious fruits you won’t find in stores.
Tomatoes have a delicious taste when grown in a warm, sunny climate. Remember that tomatoes need heat and light to ripen properly and develop their flavor.
If you’re just starting with gardening or your area has challenging water conditions, you may use our tips to grow tomatoes successfully.
Some of the information in this article comes from my own experience.