Tomato plants will keep growing as long as you let them, and as long as they are not hit by frost. But, as you get towards the end of the growing season, you may find that your tomatoes won’t ripen and turn red. In this article, we look at 7 ways to help you get as many ripe tomatoes from your plants as possible.
As it gets towards the end of summer, I always get a bit fretful about the plants that are yet to flower, the herbs that are getting woody and the fruit that has yet to ripen.
And, some of the questions I most often find myself asking is these: why are my tomatoes not turning red? Why are my tomatoes not ripening, why are my tomatoes staying green and turning red?
You get the picture, I expect: I can get a bit obsessive about my tomatoes (as you can also see from the tomato grower’s story below)!
Anyway, here I set out 7 easy techniques to help you bring your tomato growing efforts to fruition when your tomatoes are not ripening on the vine. But first let’s answer this question:
Why your tomatoes are not turning red
Even if your tomatoes are big, they may not be turning red. There are 3 main reasons why tomatoes fail to ripen and turn red:
- Too much heat: tomatoes love heat, but not too much. Prolonged extreme heat stresses the tomato and causes it to to stop developing;
- Too much cold: tomatoes stop producing the carotene necessary for ripening if temperatures get too low, as often happens at the end of the season (this is the problem I usually have);
- Too much feeding and watering: tomatoes that are too well pampered just keep putting on fresh new growth instead of diverting their energies to seed production through ripening their fruit.
Note this applies to cherry and roma tomatoes that are not turning red, as much as to any other green tomatoes.
The tomato grower’s story
You’ve spent all summer carefully nurturing your tomatoes.
You’ve sown the seeds early in Spring, dreaming of eating juicy ripe tomatoes with fresh bread, mozarella and your lovely home grown basil.
You’ve seen them germinate and pricked them out into pots. You’ve grown them on, watered them and potted them on again.
You’ve improved your soil, planted them out in the garden or into a growbag in your greenhouse.
You’ve watered them, weeded them and fed them once they set fruit.
You’ve worried about the brown or purple tinges you might have seen on some of the leaves, googling to see what it might be.
You’ve pinched out the sideshoots, including the ones that appear out of nowhere at about 60cm long that you somehow missed a week or two earlier.
And you’ve watered and fed them some more.
If truth be told, and it a little bit like your plants, you’ve probably got a little bit stressed on those hot days when the plants are wilting and it looks like you’re going to lose them. And you’ve been very relieved when they regain their strength and perk up in the cool of the evening.
And with the plants laden with green fruit, you’ve rejoiced at the first sight of an orange blush on one of the tomatoes, and you’ve checked on its progress every day.
And finally, on a day that it seemed would never arrive, you carefully picked your first tomato.
You hold it carefully in your hands, you feel its warmth and you smell its unique tomato aroma. You carry it triumphantly inside to receive the acclaim that it, and you, deserve.
Then they come thick and fast. There are tomatoes ripening day by day.
It’s tomato salad, tomatoes in your sandwiches and maybe even fresh tomato juice with your vodka.
Until suddenly they are not coming so thick and so fast.
The days are getting shorter, the heat of summer is dissipating and there are a still a lot of lovely green tomatoes that are not ripening on the plant.
So you start to worry: “why won’t my tomatoes turn red?” After all, if your tomatoes are not turning red, a lot of your hard work and effort over the months is going to have gone to waste.
Tomatoes not ripening? Here is what to do if your tomatoes are not turning red
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Take these 5 steps to get your green tomatoes turning red. These techniques apply to all tomatoes, including cherry tomatoes that are not ripening:
- Stop the plant
When your tomatoes are not ripening on the vine, you first need to stop the plant putting any more energy into growing, so that all the energy goes into the existing fruit. This means you need to pinch out or cut off the plant at the top growing point, so that it won’t get any bigger. You can see where I have done that in the picture below.
Also, cut off any flower trusses that have not yet set fruit, or have only tiny fruit, because these will not be able to grow enough in the time that is left in the growing season.
- Pinch out side shoots
Tomatoes are vigorous plant. So despite all your best efforts, side shoots keep coming back. You should have been pinching out side shoots as the plants has developed, but now is the time to keep a keen eye on this and keep pinching them out. This, again, is aimed at making sure the energy goes into ripening the fruit.
You can see a new side shoot developing in the picture below, even though it is late in the season and I have pinched out shoots from that spot before.
- Cut back the foliage
You need as much light as possible to get to your tomatoes. It is really warmth that ripens the tomatoes, rather than light. But as the strength of the sun weakens in Autumn, it’s best to get as much direct sunlight on to the fruit as you can to maximise the amount of warming they receive.
Now that you don’t want the plant to grow any bigger, it does not need so many leaves for the photosynthesis that fuels its growth. So, in late August or early September (Northern hemisphere), you can cut off half to two thirds of the plants leaves, making sure especially to take off those leaves that are preventing light and warmth getting to the fruit. Later in September/October, you can take off more or less all the leaves.
This picture is from early October and you can see that I have removed most of the leaves from these plants now.
- Put a plastic bag over the tomatoes on the vine
It is really the heat that has the biggest effect on ripening tomatoes. If you tie a plastic bag over the tomatoes on teh vine, this will increase the heat. Since they are still on the plant, they’ll remain fresh and still be sweet when you harvest them.
- Put them in a bag – with a banana
If all else fails and the tomatoes are not ripening on the plant, you can pick and place the unripe fruit in a paper bag with a banana in a drawer or other dark place. Bizarre as it sounds, this works because the ripe banana gives off ethylene and ethylene promotes ripening in fruit.
This works best with fruit that are showing signs of starting to ripen (i.e. a hint of orange flesh). Also, check regularly for any signs of rotting and remove any fruit that are starting to rot. - Hang the plant upside down
Another method (an alternative to the banana in the bag trick) is to pull up the plant and hang it upside down somewhere warm dry and away from frost (e.g. a garage). You probably won’t get all the fruit to ripen, but in this way you can harvest a few final fruits of your labours.
- Put them in a bowl in a warm place
This is probably the simplest method, and for many it works really well. Simply put your green tomatoes on a bowl in a warm place – often a sunny windowsill works – and wait. With enough warmth, your tomatoes will start to ripen.
So there you have it. Don’t let all your efforts go to waste. Try these techniques for ripening your tomatoes.
Frequently Asked Questions
When do tomatoes ripen?
Tomatoes need warmth and sunshine to ripen fully. Green tomatoes will begin to ripen once daytime temperatures reach 55 to 60 degrees Fahrenheit and nighttime temperatures stay above 50 degrees.
The ripening process speeds up as temperatures climb into the 70s and 80s. With the right conditions, tomato plants can continue producing ripe fruit through the first fall frost. Gardeners in cooler climates can extend their tomato harvest by moving plants into a greenhouse or sunny windowsill as summer transitions to autumn.
When should you pick tomatoes?
There is some debate about this. Some say you should wait until they are fully red before you pick tomatoes of the vine. This is what I do, and I think it works because we live in a relatively cool climate. If you live in a warm climate, there is a risk that ripe tomatoes can over-ripen, become mushy and split.
Some people take the view that tomatoes can develop better flavour if picked just before fully ripe. At this stage, they are bright green with a tinge of pink or yellow.
If you pick before they are fully ripe, then, assuming you are in a warm climate the tomatoes should turn red and become juicy and sweet. The best test of ripeness is smell – a ripe tomato will give off a strong, sweet aroma. Refrigerating tomatoes halts the ripening process, so keep them at room temperature for best flavour.
How can I make sure my tomatoes have the best taste?
The key to maximising tomato flavour is allowing them to fully ripen on the vine. In warm areas, tomatoes should be left on the plant until just before they are fully ripe, when they have turned from green to pink or light red.
At this ‘breaker’ stage, pick the tomatoes and let them finish ripening indoors at room temperature out of direct sunlight. This enables them to slowly develop complex flavours as their sugars concentrate. For sweeter tomatoes, choose heirloom or grape/cherry varieties which are naturally higher in sugar content.
In cooler areas, let them ripen on the vine for as long as possible, but watch that they don’t over-ripen and split, or get attacked by pests.
What you need
The most important tool that you need is a good pair of secateurs for cutting back the foliage and stopping the plant.
I only ever use Felco secateurs, which in my experience have proven to be the best and most reliable secateurs around. I use the Felco number 2 as it is a good all-round secateur.
US Buyers
- This size is for medium to large hands
- Efficient: easy, durable cutting adjustment / wire cutting notch / sap groove
- Ergonomic: hand protection is provided by the cushion-shock absorber / non-slip coating
- Comfortable, lightweight, sturdy aluminium alloy handles
- High quality hardened steel blades, forged aluminium alloy handles, wire cutting notch
- Anvil blade with sap groove, rubber cushion shock aborbers
- For a medium to large hand, right Handed; the handles have a non slip coating
- Lifetime guarantee, all parts replaceable
- The Felco 7 Orcharding and Garden secateurs is best used for cutting tasks in your garden. It is best suited for twigs and plants with a diameter not larger than 2.5 cm.
- The box contains the garden and orcharding secateur that is equipped with a wire cutting notch and a sap groove.
- The shear provides a clean and precise cut for twigs and other plant parts up to a diameter of 25 mm.
- The one-hand pruning shear has an ergonomic design through a hand and wrist protection and an optimisation of the force by a revolving handle. Furthermore it is equipped with a non-slip coating.
- The sturdy handles are made of forged aluminium whereas the blade and the screw-mounted anvil blade are fabricated out of high-quality hardened steel-
- Carbon steel blades with chromium coating to prevent corrosion and make blade crossing smoother
- Blades with sap groove
- Straight blades with rounded ends for precise cuts without damaging the fruit
- Polyurethane shock absorbers to reduce muscle tension
- Stainless steel pin spring for smooth movement, which reduces muscle tension + Pressed blackened steel handles for optimum durability
Last update on 2023-11-28 / Affiliate links / Images from Amazon Product Advertising API
UK Buyers
Felco Number 2
Felco Professional Model 2 Secateur
The Felco model 2 bypass secateur is a popular and high quality product, used and highly recommended by gardening professionals. It features:
- comfortable lightweight, easy to grip handles,
- a hardened steel blade with a wire cutting notch,
- riveted anvil with sap groove to allow plant fluids to drain away
- a toothed centre nut mechanism which easily aligns the blades for a clean precise cut
- a rubber cushion shock absorber that protects the wrists.
Felco No 2s carry a lifetime guarantee and all parts can be replaced, so it is easy to see why these are the secateurs of choice for many horticulturists and serious home gardeners.
21.5cm/8.5" overall length can cut stems up to 2.5cm/1" in diameter.
Weight 240g/8.5oz
Felco Essential
Felco Essential Secateur
The Felco Essential Secateur is the entry level secateur made by Felco, the renowned Swiss master secateur makers.
Designed for larger hands, these secateurs are suitable for all general pruning and cutting work.
This model features an ergonomic grip made from high tech composite materials for comfort and a finely machined alloy professional cutting head, for efficiency of cutting.
Measures 21cm (8.25”) in length
Weighs in at only 190g (6.7oz)
Learn more about growing edibles
Check out these posts for more on growing your edible plants:
How to grow zucchini – this is the ultimate guide to growing this delicious squash.
How to prune your tomatoes and pinch out your tomato side shoots.
How to get the best out of your basil plants.
Here is how to prick out your tomato seedlings.
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Martin Cole has been an avid gardener for more than 20 years and loves to talk and write about gardening. In 2006 he was a finalist in the BBC Gardener of the Year competition. He is a member of the National dahlia Society.
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Thanks! It’s hard to find answers to why our tomatoes won’t ripen. But although most of them are turning red, the cores are hard and the tomatoes are not soft and juicy so we left them on the vines too long, I think. I’m trying the banana trick for sure!!