The first thing you need to know is that sunlight isn’t always helpful; in fact, too much light can toughen skins, so don’t put your tomatoes on the windowsill. If you grow tomatoes, don’t be tempted to pull the leaves off the plants to help them get more sunshine.
Tomatoes need warmth to ripen. The warmer a tomato is, the quicker it will ripen – putting your tomatoes in the fridge is therefore no help to them at all, and can even degrade their texture to ‘mealy’. However, if tomatoes get too hot, the ripening will stop – another reason to keep them off the windowsill.
Tomatoes, like bananas and avocados, give off ethene (or ethylene) gas, a natural plant hormone that regulates a plant’s growth and makes it ripen by converting the starch it stores into sugar. All fruits do this, and tomatoes are technically a fruit, which is why they will ripen other climacteric fruits (fruit that will ripen off the plant that it grows on).
As long as you are start the process with tomatoes that have naturally started to ripen (even if they have only just started to tinge yellow or orange in patches) these will be ready to ripen, and will have a better flavour when they turn red. Tomatoes that are completely green may not develop as good a flavour or ripen as well, so perhaps think about using them in a recipe such as green tomato chutney.
How to ripen tomatoes
In a breathable bag or box
3) Fruit gives off moisture, so use a bag or box that won’t trap it and keep the tomatoes spaced apart so they don’t go mouldy.
4) Ripening from very unripe usually takes a week or two at higher temperatures (18C-25C is optimum) – just keep checking as the tomatoes will ripen at different speeds.
5) If it’s cold in your kitchen, ripening will take much longer. Also, check for tomatoes that start to rot, as these will affect all the others.
There is some advice available that tell you to put tomatoes in a jar, but this is more likely to trap moisture and hasten spoiling.
In the fruit bowl
If your tomatoes are almost ripe but just need a little more time, keep them in your fruit bowl. The fruit around them will give off ethene and help them to ripen, and you will be able to keep an eye on them.
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All the best Jan