Why Aren’t My Tomatoes Turning Red?

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Growing your tomatoes is great. It’s not only self-sufficient, but it also gives you an incredible feeling nurturing a seed into a yummy harvest. When you grow your tomatoes, you will expect to see them starting to turn a bright red as they ripen. 

But what if your tomatoes are nearing their harvest date and show no signs of changing color? Is there anything you can do about it? Keep reading to find out why your tomatoes may be taking longer than they should to ripen and if you can fix it. 

Please read: This information is provided for educational purposes only and is not intended to treat, diagnose or prevent any disease. We encourage you to make your own health care decisions in partnership with a qualified health care professional.

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What Causes Tomatoes To Turn Red?

The tomato plant takes about three weeks to grow to about 45 cm / 18 inches. At this point, it should produce fruit that will mature after 3 weeks or so. Both the plant and fruit are filled with chlorophyll at this stage to help the plant grow.

When the tomatoes are approaching maturity, they produce a hormone known as ethylene, which causes the tomato to produce lycopene, giving the red pigment. 

Why Aren’t My Tomatoes Ripening?

There are several reasons why tomatoes don’t ripen when they should. Here are some of them.

It’s not yet time

Tomato varieties have different maturity periods. The reason your tomatoes aren’t turning red may be that it’s not yet their time. While most tomatoes will ripen in about six weeks, maturity time may be different for some varieties. 

Also, the smaller types like cherry tomatoes will start to turn red before the bigger ones. So, you may just have to wait a little longer. 

Temperature is too hot

If temperatures are warmer than usual, it could cause the tomatoes to stay greener for longer. This is because the hormone ethylene that causes ripening is temperature-sensitive. It works best at an optimum temperature, which is not too hot.

If the temperature exceeds normal, the ripening process may slow down or even stop altogether. Instead of the tomatoes turning red, they may change into an odd color like an orangey pale green, but they won’t turn red.

Uncontrolled vine growth

The process of ripening takes some energy from the plant. For this reason, if the vine is overgrown, it could be using its energy to support this excess growth at the expense of the fruits. If the vines are tangled and bushy, it’s a sign of overgrowth.

It’s too cold

As mentioned before, tomatoes ripen at an optimum temperature, around 20 – 25°C /  68 – 77 °F.

If the weather is too cold, the enzymes that cause ripening will work slower than they should. Therefore, it will take a bit longer for your tomato fruit to turn red. In icy conditions, there are minimal chances of getting ripened fruit from your vines.

Local climate

Some varieties of tomatoes work better in other regions than others. Your tomatoes are not turning red because the type you planted is not suitable for your local climate.

If you live in an area where the climate fluctuates, it helps to plant quick maturing varieties. Put in the extra research before planting your tomatoes so that you can pick the ideal type for your locality.

That’s their color

You may need to double-check the particular variety of tomatoes you planted. Not all tomatoes are red. Some are green, purple, yellow, or other colors depending on the variety. That green or yellow color that won’t go away may be the right color for the type of tomatoes that you planted.

Sun scalding

Some parts of the tomato may get scalded and turn into a greenish-yellowish color. Scalding is like the tomato getting sunburnt. The part of the tomato that’s not red may never ripen and instead, start to rot.

Mineral imbalance in the soil

Mineral salts such as potassium and magnesium help to ‘feed’ the soil. This keeps soil healthy, and the plants can grow well. However, they have to be balanced to get the best crop. If there is too much magnesium and too little potassium in the soil, the tomato plants won’t ripen as expected. Instead, they will be discolored or get a condition known as yellow shoulder disorder.

Is There Anything I Can Do To Encourage Ripening On The Vine?

Harvesting green fruit can be disheartening, especially if you put them in the house only to have them all rot. After all that hard work, no one wants to have to deal with that. Here are a few tips to help your tomatoes turn red on the vine.

Pruning the vine

As mentioned earlier, the tomatoes may be putting energy towards the stalk instead of the fruit. Therefore, to avoid that, you will need to prune the tomato plant. You do this by removing excess leaves from the plant. This will help it to focus on the growing fruit, ultimately encouraging faster ripening. You don’t have to wait until it’s almost time for maturity to prune; it helps to start early. 

As soon as the fruits start to grow, start getting rid of the bottom parts of the stem and leaves. Leave only the ones near the fruit. Apart from stimulating ripening, this can help improve aeration and ward off some diseases.

Remove the smaller tomatoes

As heartwrenching as it may be, you will have to pluck off the smaller tomatoes to give the bigger ones a fighting chance. By removing the smaller ones, you allow the tomato plant to concentrate on the larger fruit, which might ripen faster.

Keep out the cold

When it’s the surrounding temperatures are cold, tomatoes may have a hard time ripening. To prevent that, give your plants some extra protection. Here are some ideas for keeping the cold out.

• Cover the plants with a sheet or blanket. Use stakes to stretch out the cover around the plant but check that the blanket doesn’t touch the plant. If you don’t have any cloth material at hand, you can use plastic or sackcloth. However, make sure you don’t place it over the plant but rather around it. 

• Put on some extra mulch to keep more moisture in the ground to help protect from the cold. 

• Another way of keeping your plants warm is to hang a light or lamp in the plants’ vicinity. This light should give off some heat, which will help the plants.

• Eliminate new growth. Any new suckers or flowers are useless at this point. Therefore, to encourage the fruit to ripen, cut them off. 

What If The Tomatoes Still Won’t Ripen?

If the tomatoes are still not budging, you can pick them from the plant and get them to ripen indoors. It’s important to remember that this will only work when your tomato fruit has a mature green color. 

If you are wondering how to tell the green colors apart, simply look at the glow and shade of the green tomato. The mature green color will be glossy and almost pale green. If it’s still a darker, dull green, this won’t help.

Easy Tricks To Help Turn Your Tomatoes Into A Bright Red Color

Put them in a paper bag

You can place the tomatoes inside a paper bag together with one ripe tomato. This will help to encourage ethylene production, making your fruit ripen faster. However, you have to make sure you check on the tomatoes regularly and take out any that have turned red. If you don’t, they may start rotting and cause all the other tomatoes to rot as well. 

Leave them on the counter

Tomatoes produce enough ethylene to ripen on their own even when they are not attached to the vine anymore. So you can simply leave them on the kitchen counter or anywhere else with enough light, and they should start ripening on their own. It’s important to remember, though, not to put them in a dark place like the cupboard.

Put the whole plant indoors

If you have only one or two ripening tomatoes on the plant, you can uproot the entire plant and hang it with the roots facing upwards in a well-lit room. Be careful not to damage the roots during transplantation. You can tie the plants in a bunch and hang them on the rails or behind the door. 

To Sum It Up

There are several reasons why your tomato fruit may not turn red when you expect it to. If this happens, you can try to encourage ripening. If the worst comes to the worst and they still refuse to turn red, you may have to pick the mature green tomatoes and use these tips to get them to mature inside the house.

We hope you found this helpful, and you’ll soon be enjoying some fresh, bright-red tomatoes.

Why aren't my tomatoes goin red? If you are struggling with tomatoes not ripening on the vine, here are some reasons they aren't and how you can make your tomatoes ripen faster.

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