Why aren't my tomatoes turning red? Experts explain the various reasons your homegrowns won't ripen

Lilith Hudson

September 3, 2023 at 2:30 PM·4 min read

A group of tomato plants in terracotta pots

After planting your tomatoes at the start of the season and diligently watering them every day since, you'd hope your patience would have paid off with a harvest of ruby red gems by now. The best part of late summer for any vegetable gardener is that you finally get a chance to enjoy the sweet fruits of your labor, so if you're still waiting, you're probably pretty frustrated.

If you're here, it's because the homegrown tomatoes in your vegetable garden are yet to turn red. Every day you hold out hope that a small blush of orange might have appeared, but alas, here you are, weeks after they pollinated and hungry for a tomato salad. Where did you go wrong, and is the onus actually on you or are external factors to blame?

To find out, we spoke with some professional gardeners who know a thing or two about growing the perfect tomato crop. Here they explain the various reasons why yours won't ripen, alongside some alternative ways to put those green tomatoes to good use.

Why aren't my tomatoes turning red?

You watched them grow, then flower, then form the delicious fruits that you're now dying to eat. All they need to do now is ripen, but why are they taking so long? 'It's usually because they haven't reached the mature stage, which is essential before they can ripen and turn red,' explains Tony O'Neill, plant expert and owner of Simplify Gardening.

There are various issues that could be the culprit, with the most common being insufficient light, improper temperature, or a nutrient imbalance. 'Generally, the weather has the most influence,' says Craig LeHoullier, tomato expert and author of the book Epic Tomatoes, available at Amazon. 'Cooler weather may delay ripening for a week or so while really hot weather can hasten it, but in general tomatoes on a plant will ripen when full development is complete. The timing for this can vary widely depending upon the particular variety.'

If you've had your tomato plants in a shady spot in your backyard, then the blame's on you. Tomatoes require at least 6-8 hours of direct sunlight a day to grow properly so should always be placed in a sunny spot. If, however, you've been cursed with poor summer weather with cooler temperatures and overcast skies, cut yourself some slack and hope for some more sun next summer. We can't control everything, after all - especially not mother nature.

Craig also notes that depending on the variety of tomatoes you're growing, perhaps you shouldn't expect them to turn red at all. 'Tomatoes ripen according to the genetics of each variety,' he says. 'Some turn red, yellow, or orange, while others stay green even once they've reached maturity.'

How long does it take for tomatoes to turn red?

A tomato plant in a basket container hung on a wooden fence

Growing edible plants takes patience, and if you hold out long enough, there's a high chance your tomatoes will turn red eventually. The question is, how long is too long to wait?

'Weather can influence this, and the genetics of particular varieties are the key factor, but a rule of thumb is that it will take three to four weeks from a pollinated blossom (that shows the tiny green developing tomato) to fully ripe tomato,' explains Craig.

If your tomatoes stopped growing in size long ago but are still showing no signs of turning red, it might be time to give up. 'If a tomato hasn't started turning red within 40 days of reaching the mature green stage, it might be too late, and the fruit may not ripen properly at all,' Tony adds.

What should I do with tomatoes that won't ripen?

A tomato plant - which requires a lot of water to flower

So you've admitted defeat and faced facts that your green tomatoes aren't ripening, but what do you do with them now? Thankfully, there's absolutely no reason to throw them away or compost them - instead, you can put them to use in your kitchen with some less traditional tomato recipes.

'You can actually eat tomatoes that haven't turned red but they will be more acidic and less sweet than fully ripe tomatoes,' says Tony. 'Instead, green tomatoes can be pickled, used to make chutney or relish, or finely chopped up to make a green tomato salsa.'

Craig also suggests a dish of fried green tomatoes. 'Slice the tomatoes, dip them in beaten egg, then dredge in bread crumbs and fry until browned,' he says. Who knows, you might actually find that green tomato recipes are more to your taste, anyway! At the very least, it makes a change from another bog standard salad as we head into fall...