Gardening experts share the secrets to ripening stubborn green tomatoes

Have you had an impressive tomato harvest this summer but been left confused as to why your green fruit isn't turning red? You're not alone, which is why we've spoken to gardening experts to find out the best ways to ripen tomatoes.

Whether you're enjoying vegetable gardening as a beginner or have been doing it for years, sometimes our crops can surprise us and act out of character. With seasonal tomato harvesting, you may have found that your fruits aren't ripening like they should be.

Before you panic about being surrounded by green fruit, according to experts there are a few things you can do to fix this and prevent it from happening next harvest.

How to ripen green tomatoes

Aside from knowing how to prune your tomato plants, a big part of their growth and success is the ripening process. While many tomatoes will probably ripen when they are growing on the stem, it's more common for gardeners to remove the fruit while it is still green and ripen them indoors. But what happens when they don't appear to be turning red?

"Tomatoes will often ripen quickly if they are kept in a light, warm environment, and it is best to leave the fruits on the vine for as long as possible for the best flavour. However, if you have tried everything to ripen the fruits on the vine, you can try to ripen them indoors," says Graham Smith MCIHort, a gardening expert from LBS Horticulture.

Graham Smith MCIhort

Graham has extensive knowledge in the horticultural and gardening industries, and prides himself on using this to help gardeners of all skills create their perfect outdoor space.

1. Move the plant indoors

In the same way, there are tender plants to bring indoors in the autumn, bringing in your tomatoes will help with the ripening process.

Graham says, "Transfer your tomato plant somewhere indoors to allow the fruits to ripen on the vine, and this can lengthen the lifespan of the plant as it would not survive outside in the cold weather."

Knowing which plants to bring inside or under shelter is the best way to protect them from the frost during the winter.

2. Leave on your kitchen worktops

After you've organised your kitchen counters you should have lots of spare room, which is just what you need for ripening tomatoes.

"Unripe tomatoes that are left on a kitchen worktop will gradually ripen on their own. They should be stored at room temperature with their stems intact and the stem side facing downwards," advises Graham.

You might be tempted to pick tomatoes off the stems before bringing them in but it's the stem that helps encourage the ripening process so remember to cut a branch at a time.

3. Use a paper sack

Similar to some of the best expert cleaning hacks, finding solutions to domestic problems like your green tomatoes can often be a little unique.

"The trick I always use is to pop unripened tomatoes in a paper bag with an apple or banana," says Georgina O'Grady, managing director at Evergreen Direct.

"These fruits give off ethylene gas, which speeds up the ripening process. Some people suggest using newspaper but I’d go with a paper bag for better airflow and more even ripening."

Georgina O'Grady

Georgina is an accomplished professional in the field of interior and exterior landscaping using plants, trees, and green walls. Georgina is currently serving as the Managing Director at Evergreen Direct.

FAQs

Will green tomatoes ripen after they've been picked?

If you've rushed the process and picked off your tomatoes, perhaps trying to keep up with your succession planting, then it's not the end of the world.

"Green tomatoes will ripen after they have been picked, but you should cut open one tomato first to check that they will not begin to rot before they can ripen properly," says Graham.

To check that they can ripen properly he says you need to choose an average-sized tomato from the bash you want to ripen and cut it in half.

Graham explains, "If the gel-like material holding the seeds is still liquid and the seeds move when you cut through the fruit, tomatoes that are this size and above will ripen. However, if the gel around the seeds is not yet loose enough to allow the seeds to move away from the knife blade, then this can indicate that the tomatoes may start to rot before they can ripen."

Do green tomatoes ripen on the windowsill?

You may have heard the windowsill trick is an easy gardening tip but most experts would warn against this. In fact, they say it's best to avoid the windowsill and direct sunlight altogether.

"Green tomatoes can ripen after being picked, but they need to be at the "mature green" stage, where they’ve got a slight bit of colour starting at the blossom end. A lot of people think you need to stick them on a windowsill, but direct sunlight isn’t actually necessary and can lead to uneven ripening," explains Georgina.

Instead, she says simply putting them in a warm spot works much better and failing that throwing them in the fruit bowl moves things along quicker.

What does it mean if green tomatoes aren't ripening?

You can have all the essential gardening tools and all the best gardening knowledge, but sometimes your plants just won't behave. So if you're green tomatoes aren't ripening no matter what you do then that's normal.

Georgina says, "If they’re just not ripening, it could be because they were picked too early or they’ve been exposed to colder temperatures. Check the temperature, make sure they’re warm enough, and be patient - it’s all about giving them the right environment."

If you've done the check like Graham recommended and there is just no hope in them ripening, we'd advise you to either try out some green tomato recipes or simply compost them to enrich your soil for next year's batch.

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Graham also warns against over-fertilising your tomato plants when growing them, as this can provide too much nitrogen that will stunt their ripening process. Certainly don't use your coffee grounds on them, there are plants that are better suited to the nitrogen and potassium found in the grounds.