October tends to see the first frosts in much of the UK and as tomato plants won’t survive a frost, gardeners growing tomatoes not lucky enough to have a heated greenhouse are struggling to get those stubbornly green tomatoes to ripen.
If you are wondering how to grow tomatoes so that they have the best chance of turning red you will be interested to know that temperature has a major impact on ripening. If your fruits are too cold they will not turn red. To give your tomatoes the best chance of ripening properly you should ensure your tomato plants are maintained at the correct temperature throughout the entire growing process. Tomato seeds need a temperature between 18°C and 22°C (68°F to 75°F) to germinate and tomato plants won’t survive below 10°C. It is also important to grow them somewhere where they are exposed to as much natural sunlight as possible to aid photosynthesis.
A Helpful introduction to tomato growing
Many growers make use of seed propagators such as the Greenhouse Sensation Vitopod to ensure their seeds are kept at the optimum temperature for germination. The Vitopod is particularly useful compared to traditional tomato pots in a basic propagator, because it is large enough to be used for hardening-off and protecting young tomato plants from late frosts. The shock of a late frost to a young tomato plant just out of a heated propagator can kill the plant, resulting in you having to start again.
Obviously greenhouses, polytunnels or even a conservatory are the ideal environment in which to keep your tomato plants warm but many people do grow outdoors, just make sure you choose a bright spot and be aware that they will take longer to ripen because of the cooler temperatures.
Even though October can be a particularly bountiful month and with aids such as the self-watering tomato pots such as the hydro grow system you can sometimes harvest fruit through to December providing that the plant is located in a heated location such as a greenhouse. The season is never long enough to ripen every single tomato you grow on the vine. Consequently no matter how particular you are with caring for your tomato plants it is inevitable that if you have produced a bumper crop you will end up with a lot of green fruit. If your vines are groaning with green tomatoes there are a couple of methods you can employ to encourage them to turn red:
One solution commonly advocated in gardening circles is harvesting the green tomatoes and placing them in close proximity to a banana. This works because ripening bananas give off ethylene — an odorless gaseous organic compound which also occurs naturally in tomatoes and catalyzes the ripening process.. Tomatoes produce their own ethylene once they have reached the mature green stage of their development but the process can be speeded-up by placing tomatoes near ripe bananas, the ethylene produced by the bananas stimulates the ripening process normally stimulated by the tomatoes own ethylene, this can be blown away if they are being grown in a windy environment.
How to get green tomatoes to ripen
One way of employing this method is by selecting three or four green or yellow tomatoes and placing them in a box with a banana which is starting to ripen. Ideally the banana should be at the stage where it is still green in places but turning yellow. This process will take one or two weeks so you may have to change the banana at some point. Alternatively you could just place a few tomatoes in a sunny spot near a bunch of bananas. Many growers use apples instead of bananas for this technique due to their abundance in British gardens (unlike bananas)!
Another way of encouraging your green tomatoes to turn red is by placing the fruit in a closed paper bag on its own. This traps the ethylene which the tomato produces itself and accelerates the ripening process. Simply place the fruit in a brown paper bag, folding the top over it twice to seal it. Regularly checking to see if the fruit is ripening is important to ensure that it doesn’t start to rot, especially in a humid environment such as a home.
If you are thinking of growing tomatoes at home the Greenhouse Sensation site has some excellent information about the varieties to grow, how and when to sow tomato seeds.