4 reasons your tomatoes aren’t turning red – and how to get them back on track in time for summer salads

Why aren’t my tomatoes turning red?

If you’ve found yourself wondering why your tomatoes are still green this far into summer, you’re not the only one: even if you’ve mastered the art of growing tomatoes, fruits that refuse to turn red are a really common problem.

Well, tomatoes can be quite fussy when it comes to ripening, and it can come down to a few factors. Here are some of the most common ones – and how to fix them.

1. It's too hot

Tomatoes like warm conditions, it’s true, but if it’s too hot, they’ll struggle to produce ripe fruit. Since it’s difficult to keep your garden cool during a heatwave, your tomato plants have likely been struggling this summer.

‘Tomatoes require plenty of sunshine to grow, but don’t like too much heat, so it’s best to provide some shading,’ explains David Glass, head gardener at Bowood House and Gardens.

If you’re growing tomatoes in pots, try moving them to a shadier spot in the garden. If they're in a greenhouse, though, there are a few ways to provide that additional shade without moving them.

‘Paint greenhouse glass in the warmer months to reflect sunlight and reduce the temperature inside,’ suggests David. ‘This can be washed off later in the season to increase light levels.’

You can buy AMK® Vitax Summer Cloud Greenhouse Shading from Amazon. Of course, low temperatures can slow down ripening, too, so make sure your plants aren’t sitting chilly.

2. You're giving them too much water

If you’re wondering why your tomato leaves are curling, it’s often down to your watering habits – but overwatering your plants can reduce their fruiting potential, too.

‘While tomatoes do need regular watering, too much can hold them back,’ explains Nick Wood, horticulturist at GardeningExpress.co.uk. ‘Overwatering can delay that lovely red colour you’re waiting for.’

If your tomatoes are still refusing to turn red, you can always try Monty Don's banana hack for green tomatoes.

3. They're lacking nutrients

Whether you’re growing tomatoes in hanging baskets or a vegetable bed, they’ll need plenty of nutrients to produce a heavy crop of red tomatoes.

‘To help them along, go for a fertiliser that’s higher in phosphorus, which will encourage ripening,’ advises Nick.

Bowood’s head gardener, David, recommends feeding your tomatoes weekly to help them turn red. Levington Tomorite Liquid Tomato Food, available at Amazon, is a popular all-rounder.

4. You're not pinching them out

Ever heard of ‘pinching out’? It’s a simple pruning technique that encourages flowering and fruiting plants to channel their energy into existing trusses. If you’re growing a cordon variety, not pinching it out could be a reason why your tomatoes aren’t turning red.

‘After a tomato plant has produced five trusses of fruit, I recommend you stop the plant from growing further by removing the growing tip of the main stem,’ explains David. ‘This encourages the plant to use its energy to ripen the existing fruit, rather than continuing to grow new trusses.’

It’s good practice to remove some of the lower leaves on the plant, too.

‘Cut some of the lower leaves off the stem to allow more light in and increase the air flow around the plant,’ David adds.

There could be various reasons why your tomatoes aren't turning red, but if you cover the above bases, your tomatoes should stand a better chance of ripening.