Tomatoes are probably the most popular fruit home gardeners grow. Even though it is not technically a vegetable, it is also one of the most popular plants in any vegetable garden. After all, there’s nothing quite as good as picking a ripe, red tomato off the vine and eating it while it is still warm from the sun.
But how do you know when your tomatoes are going to turn red? Tomatoes turn red when they mature and ripen, usually 6-8 weeks after the flowers have been pollinated. Since you can sow tomato seeds throughout the spring and summer months, this means you could be picking ripe tomatoes from late spring until into the fall.
How do I get my tomatoes to turn red?
If you’ve grown tomatoes before, you’ll know that the natural ripening process will eventually turn the tomato fruits red. Though, with all the varieties available, some tomatoes don’t turn red.
They ripen to orange, yellow, pink, purple, red, and even green! For example, Green Zebra tomatoes are green with stripes, and they ripen to two different green colors.
Also, different varieties suit different climates and growing areas. So, choose with care and know what color your ripe tomatoes are going to be.
Unless there is a particular issue, like too much heat during the day or nights that are very cold, there’s nothing you need to do to get your tomato fruit to ripen.
How long does it take for a tomato to turn red?
It usually takes 6-8 weeks from the time tomatoes are pollinated until the fruit reaches maturity. Of course, some variables will affect this, including the variety of tomatoes you are growing as well as weather conditions, specifically very hot weather.
It certainly won’t be a lack of pollination that will stop your tomatoes from turning red. Tomatoes are self-pollinating, which means there are male and female parts on their flowers.
The pollen will fall into the flower, pollinating itself. The wind and insects, like bees, also play a role, shaking the pollen off into the little yellow flowers.
Of course, it’s a no-brainer that tomato fruit starts out green, even if they are a variety that will end up pink, purple, or another non-red color. They get the color from chlorophyll.
Then, as they mature and ripen, they produce ethylene, which makes the fruit change color – most commonly red. Once the seedlings are established, it usually takes tomato plants about three weeks to flower.
Once the flowers bear fruit, it takes another 20-30 days for the green fruits to mature. Then it takes another 20-30 days to ripen and change color.
What this means is that it should take no more than about two months for your ripening tomatoes to turn red. Usually, cherry tomatoes tend to ripen more quickly than other larger fruit varieties.
Reasons why your tomatoes don’t ripen
The temperature has a lot to do with the ripening process and is often the cause of tomatoes not turning red. The most common reason your tomatoes don’t ripen is high temperatures.
According to the Cornell Cooperative Extension at the University of Cornell in Ithaca, New York, the best possible temperature for ripening tomatoes is between 70 and 75°F (about 21-24°C). If it gets any hotter than 85-90°F (29,5-32°C), the ripening process slows down and may even stop completely.
The reason for this is that lycopene and carotene, which are the pigments that give ripening tomatoes their orange-to-red coloring, aren’t produced when it gets very hot. Presuming temperatures cool down a bit, this will delay rather than permanently prevent your tomatoes from ripening.
A lack of light doesn’t have much, if anything, to do with them ripening on the vine. Rather, when the fruit is exposed to direct sunlight, the increased heat tends to inhibit or prevent pigment synthesis.
The fertility of the soil doesn’t make much difference either. The folks at the Cornell Cooperative Extension point out that low levels of potassium and high levels of magnesium can result in what they call “uneven ripening yellow shoulder disorder”.
But soil conditions are not a reason why your tomatoes don’t ripen. So, adding fertilizer to the soil during the growing season isn’t going to speed up the ripening process.
Just remember that you can eat green tomatoes. They are especially good when pickled or fried. There are also some recipes that call for green tomatoes. So don’t fret if yours aren’t all turning red.
What to do when your tomatoes don’t turn red
If your tomatoes don’t ripen and/or turn red, there are a few things you can do if you want them to ripen on the vine. Otherwise, pick them and ripen them off the vine.
Steps to Take to Ripen Your Tomatoes on the Vine
A few tried and tested remedies to get your tomatoes to ripen on the vine include:
- Cut back on watering
- Keep your tomato plants dry
- Trim the lower leaves
- Pinch off the flowers if the fruit hasn’t set
- Get rid of diseased leaves
- Remove small fruit
- If it’s getting cold at night, cover your tomato plants with plastic to keep them warm
How to Ripen Your Tomatoes off the Vine
If you can’t wait for your tomatoes to turn red naturally, you can pick them and encourage them to ripen indoors. That way you have more control over the temperature that, as mentioned above, will give the fruit its color.
Some growers choose to have their tomato harvest as soon as there is a slight color change. They commonly store the tomato fruits in the dark at room temperature, which should be at an optimum 70-75°F (21-24°C), so the fruits can finish ripening.
If you opt for this approach, an enclosed environment is best. This is because the ethylene gas that is released from the tomatoes as they ripen stimulates the still-green tomatoes to ripen.
If you do it this way, the fruit of your tomato plants should develop color and flavor that is much the same as ripe tomatoes off the vine.
Have a look at the section on Tips on How to Ripen Tomatoes below for more ideas on what you can do to ensure you have red tomatoes to eat.
Tips on How to Ripen Tomatoes
If your tomatoes aren’t ripening on the vine and you decide to pick them before they ripen, here are some tips on how to ensure you get ripe tomatoes.
Tip 1: Don’t Pick Tomatoes When They Are Green
While you certainly can mature fruit off the vine, the secret is to pick your unripe tomatoes when they start to show signs that they are changing color. Don’t pick them when they are green.
Tip 2: Leave a Bit of Stem on Your Tomatoes When You Pick Them
When you ripen tomatoes off the vine, they seem to ripen more easily when a bit of the stem from the tomato plants is left attached to the fruit.
Tip 3: Don’t Refrigerate Unripe Tomatoes
If you refrigerate your unripe tomatoes, you are going to destroy their flavor and they probably won’t change color at all. You might be asking why?
Cold temperatures convert the sugar in tomatoes to starch. It’s that simple, and a reason why so many store-bought tomatoes taste super-bland.
So, eat them straight away, or let them ripen before you pop them into the fridge.
Tip 4: Ripen Tomatoes in a Paper Bag
Put a few unripe tomatoes in a paper bag. Close the bag and store it in a warm location that is more or less room temperature.
They will give off ethylene gas that will help all the tomatoes in the bag to ripen.
Tip 5: Ripen With Bananas or Apples
Pop a ripening banana or apple into the paper bag with your unripe tomatoes. The ethylene gas that the banana produces will help the green fruits ripen indoors. It will also make the tomatoes turn their distinctive red color more quickly.
Place the paper bag in a warm place away from direct sunlight and replace the banana if it ripens. It usually takes a week or two to work.
Don’t cut the apple or peel the banana or you will be likely to attract fruit flies.
Tip 6: Ripen Tomatoes in a Cardboard Box
Similar to Tip 3, you can ripen your tomatoes in a cardboard box. Place them so they don’t touch each other. This will help to prevent mold from forming.
You can add a ripe or ripening banana to the contents if you wish. It should accelerate the amount of ethylene given off.
Tip 7: Ripen on a Windowsill
People who have been using this ripening method for decades will tell you that not only will they ripen from green, but they will also ripen in full sunlight. Just be sure that the temperature doesn’t rise above the scientific optimum of 70-75°F (21-24°C).
You might not get the same delicious-tasting red tomatoes you would normally get after ripening on the vine, but they’ll still be good. If they’re not as tasty as those that have matured and ripened on the vine, use them for soups, stews, and salsa.
When do tomatoes turn red? Usually no more than two months after they have been pollinated. But what do you do if they don’t ripen and change color?
Our garden tips for 2023 will help you cope with tomatoes that aren’t ripening on the vine. You may think that this is a problem only you are grappling to solve, but it’s surprisingly common. So, don’t worry, if you follow our tips, your tomatoes will likely be great this season.