Monty Don's tips for ripening green tomatoes will give you a better harvest, even in September

Tomatoes not ripening? Use the gardening guru's clever tips to turn the green fruit red quickly

close-up of ripening green tomatoes on the vine
(Image credit: Marius Weber / EyeEm / Getty)

Monty Don's top tips for ripening green tomatoes will come in handy if your tomatoes are showing no signs of reddening. With only a few weeks of warm weather left for many gardeners, time is of the essence if you want to be able to harvest your tomatoes before the first frosts make it too cold for these plants to produce fruit. 

Growing tomatoes can be tricky in climates where summers are unreliable and steady sunshine cannot be guaranteed. However, Monty's know-how will help you maximize your tomato harvest no matter how good a summer you've had. 

Monty's top tips for ripening green tomatoes

Vertical garden ideas with tomato plant

(Image credit: Future / Annaick Guitteny)

Writing in his blog, Monty acknowledges that many gardeners will want to 'extend' tomato harvesting period beyond the peak season in August. This is especially true if warm, sunny weather has been late to arrive where you are, in which case you'll want to make the most of your vegetable garden ideas during the final warm weeks of late summer.

First, Monty recommends pruning tomato plants 'to strip off the bottom half of the leaves on each plant'. At this point in the season, you want to be encouraging your tomato plants to put all the energy they're getting into the fruit, so stripping off leaves 'will let in light and air so that the growing fruits get more sun and also the extra ventilation will reduce the risk of disease.' 

Again, doing this is very important if you've had a wet summer, as your tomatoes will be especially vulnerable to rot and fungal problems that even tomato companion planting can't mitigate. In fact, Monty advises that 'this process can be continued weekly until there are no leaves left at all.' Don't worry that the plants won't look very nice – just focus on that fruit. 

fresh heirloom ripening green tomatoes from vegetable garden on a windowsill

(Image credit: Catherine McQueen/ Getty)

This is also the time of year when you'll want to cut down on watering, 'unless it is very hot to avoid the fruit splitting.' Instead of regular watering, refocus your efforts on fertilizing your tomato plants with liquid seaweed, 'or, if you can make it, home-made comfrey feed.' As Monty points out, both of these natural fertilizers 'are ideal for maximizing flower and fruit production.'

If nothing works, and by the end of September your tomatoes are still green, gardener and author Sarah Raven advises to 'pick the green tomatoes and bring them indoors to ripen on a sunny windowsill.' So long as the fruit is of a decent size, it should still ripen at home. 

Anna K. Cottrell is now a freelance writer, having previously been a Content Editor for Future's homes titles. She writes about interior design, property, and gardening. On H&G, she specialized in writing about property – buying, selling, renting – sustainability and eco issues.