How to Ripen Green Tomatoes at the End of the Season

Every tomato grower knows the end-of-season dilemma: the plants are still loaded with fruit, the weather is turning, and half the crop is stubbornly green. Whether frost is on the way or the summer simply ran out of heat, you do not have to lose those tomatoes. Green tomatoes ripen perfectly well off the plant, and with a little know-how you can turn a glut of unripe fruit into weeks of home-grown tomatoes. Here is how to do it reliably.

The science: it's all about ethylene

Tomatoes are what botanists call a climacteric fruit, which means they continue to ripen after picking — unlike, say, strawberries. The driver is a natural plant hormone called ethylene, a gas the fruit releases as it ripens. Ethylene triggers the changes we recognise as ripening: the green chlorophyll breaks down, red and orange pigments develop, starches turn to sugars, and the flesh softens. Once a tomato has reached the 'breaker stage' — when the blossom end just begins to turn from green to pale yellow or pink — it has everything it needs to ripen fully off the vine.

The trick to ripening green tomatoes quickly, then, is simply to concentrate ethylene around them and keep them warm enough to respond to it. Everything below is a variation on that one idea.

Method 1: the paper bag and banana trick

This is the fastest and most popular method for small batches. Place a few green tomatoes in a paper bag and add a ripe banana or apple, then fold the bag closed. Bananas and apples are prolific ethylene producers, and trapping that gas in the bag with the tomatoes speeds ripening dramatically. Check every couple of days, remove any tomato that has ripened or shows signs of rot, and replace the banana once it is spent. Kept warm, tomatoes treated this way often ripen within a few days to a week.

Use paper, not plastic. A paper bag traps ethylene while still letting moisture escape, whereas a sealed plastic bag holds humidity and encourages mould and rot.

Method 2: a box in a warm room

For a larger harvest, lay the tomatoes out in a single layer in a cardboard box or tray lined with newspaper, making sure they are not touching so that one rotting fruit cannot spoil its neighbours. Pop a ripe apple or banana in among them to raise the ethylene level, cover loosely, and keep the box somewhere warm. Check it every few days and remove ripe or damaged fruit. Laying tomatoes out this way ripens them a little more slowly than the bag method, which is useful — it staggers the crop so you are not suddenly overwhelmed with ripe tomatoes all at once.

Method 3: ripening on the vine

If frost threatens and the plant is still covered in fruit, you can lift the entire plant and hang it upside down somewhere frost-free but warm, such as a shed, garage or porch. The fruit will continue to draw on the plant and ripen gradually over the following weeks. Alternatively, cut whole trusses of green tomatoes and lay them in a box. Fruit ripened on the vine or truss often develops slightly better flavour than individually picked tomatoes, so this is worth doing if you have somewhere suitable to hang them.

Temperature matters more than light

A common myth is that green tomatoes need a sunny windowsill to ripen. In fact, they do not need light at all — warmth is what counts, and a bright windowsill can actually overheat and soften fruit or scorch one side. Aim for a steady room temperature of around 18–21°C, at which most tomatoes ripen within one to two weeks. At a cooler 13°C or so, ripening slows to three or four weeks, which can be handy for stringing out the harvest, but temperatures below about 10°C leave tomatoes bland and mealy.

Warning: never put unripe tomatoes in the fridge to ripen. Cold temperatures halt ripening and permanently damage the flavour and texture, leaving the fruit grainy and tasteless. Only ripe tomatoes should go in the fridge, and even then they taste best stored at room temperature.

What to do with the truly green ones

Some tomatoes, especially small, hard, dark-green fruit that never reached the breaker stage, may never ripen well indoors — and these are the ones to cook rather than wait on. Firm green tomatoes are excellent fried, roasted, or made into the classic green tomato chutney, so an end-of-season glut of unripe fruit is a chance to fill the larder rather than a loss. Sort your harvest with this in mind: the paler, slightly softening fruit for ripening, the small hard green ones for the kitchen.

Growing tomatoes and battling other problems too — splitting fruit, curling leaves, or mystery spots? PlantMe identifies plants and diagnoses common plant problems from a photo, drawing on recognition of 500+ diseases, so you can spot what is affecting your crop and act before the season ends.