Are tomatoes not turning red? Why + How to turn green tomatoes red on vines

Tomatoes usually turn red due to the presence of lycopene. Lycopene is a carotenoid hydrocarbon that occurs naturally in fruits and vegetables.

Tomatoes usually turn red due to the presence of lycopene. Lycopene is a carotenoid hydrocarbon that occurs naturally in fruits and vegetables. It is this specific chemical compound/pigment that is responsible for giving them a red color.

Lycopene is usually found in pink guavas, watermelons, tomatoes, and even apricots. So when you discover that your tomatoes are not turning red, it may be because they lack lycopene. Now that is just one reason, in this article, we will talk about other reasons why your tomatoes are not turning red. We will also highlight ways of fixing this problem.

What causes tomatoes not to ripen?

tomatoes not turning red
Photo by Bhupinder Bagga

Your tomatoes have not reached maturity. 

Different tomato varieties have different times to reach maturity. i.e., the number of days from when it is planted to when the fruit ripens. Most tomato fruits ripen within a span of six to eight weeks after blossoms pollination. If you want a continuous supply of tomatoes, you should plant different tomato varieties which have different maturity times.

Temperatures are too cold.

For mature green tomatoes to ripen, they require an optimum temperature of 68-77 degrees. If the temperature goes below this range, the ripening process will be much slower. The ripening process may even stop if the plant is exposed to a temperature below the optimum range for long periods.

Temperatures are too hot.

As much as tomatoes love heat, extreme heat could also be a problem. When the temperature is above 85 degrees, tomatoes do not produce lycopene. So we should not expose the tomatoes to extreme heat for a very long time because the tomatoes will stop ripening. This will then cause the tomato to remain in the mature green phase for a long time.

Your tomatoes are not red tomatoes.

Some specific tomatoes do not turn red, even if they are ripe. A good example is the Heirloom tomato. If you are experimenting with new varieties, it is best if you knew what the mature stage is supposed to look like. This is because some tomatoes may ripen to orange, pink, yellow, or even green.

How to turn green tomatoes red on the vine

how to turn red tomatoes on vines
Photo by kajakiki from iStock

Here is how you can turn green tomatoes red on the vine.

  • Harvest daily. – once the fruit has begun to show color, pick it.  This will permit the other fruits on the vine to mature faster. You can then ripen the fruit that you have picked off the vine at room temperature. The tomato that ripens off the vine will be equally tasty as those that ripen on the vine, so do not worry.

Ensure that you do not leave the overripe fruits on the vine as they will make the other unripe tomatoes develop slowly. It may also facilitate the spread of diseases.

  • Remove flower clusters. – only pluck the new flowers from the plant that already has fruits. When you remove the flowers, it will direct the plant’s nutrients and energy to ripen the tomatoes that are already on the vine.  To avoid frost or cold damage, remove the flowers no later than a month before the first frost is expected.
  • Stress the plant’s roots near season end – rotate and shift plant roots by twisting carefully. As you do this, you disturb the plant’s distribution of nutrients and water from the roots to the fruits. This, in turn, will make the plant complete fruit growth, and it will ripen faster.
  • Pluck excess or small fruit. –  remove the excess and small tomatoes off the tomato plant. Removing the small fruits will ensure the plant diverts all its nutrients and energy to ripen the already mature tomatoes. If they are small and have reached the mature green stage, they can be plucked and ripened at room temperature.
  • Minimize the use of water and fertilizer late in the season – doing so will encourage mature green fruits to ripen faster. This is because fertilizers that are rich in nitrogen will promote leaf growth instead of fruit growth and maturation. You can, however, use fertilizer low on nitrogen.

When you reduce water on the plant once the tomatoes have reached the mature size, it will enhance the ripening process and also improve the flavor.

  • Remove some leaves – the tomato plant usually produces new shoots, which are called suckers. These suckers are usually found between lateral branches and the main stem. Pluck off these new growths so that the plant can direct its nutrients and energy to ripening the tomato fruits instead of developing fresh leaves.

How long does it take tomatoes to turn red?

The regular-sized tomatoes usually take 20-30 days from the flowering stage to reach the mature green stage. They then take another 25- 35 days for them to turn red (ripen). So that is a total of 45-65 days for the entire process to be complete.

Cherry tomatoes always ripen sooner than the larger fruited tomatoes. In most cases, the entire process, from flowering to ripening, takes about 42- 49 days.

Can you pick tomatoes when they are green?

picking green tomato
Photo by mgstudyo from iStock

Yes! You can pick tomatoes when they are green and ripen them off the vine. The tomatoes that you usually see at the supermarket were picked using this method. This is to allow time for them to ripen during transportation.

Some tomatoes are also heavy for them to ripen on the vine. So the easy way to ripen them is to pluck them when they have reached the mature green stage and let the ethylene gas continue ripening them.

Note: If you want to slow the ripening process, store the tomatoes in a cool place and if you want to hasten the process, store them in a warm place.

Growing tomatoes may take time, so you need to be patient. There are also different varieties of tomatoes, so you need to know which one you are planting and its characteristics. As the weather becomes warmer and favorable, the ripening process will begin. This is so, assuming all the factors are constant, and you do not stress the plant.

Also, remember that those immature green tomatoes will never ripen. You have to wait for them to reach the mature stage.