You cannot rush a tomato to ripening; it will ripen in the number of days that nature requires. And, of course, the time to ripening varies by variety, for example, an Early Girl tomato requires 60 days from setting out transplants to harvest and a Brandywine tomato requires 80 days.
The process of ripening is governed by temperature—a range of 65 to 75°F (18-24°C). As ripening occurs, the green pigment (chlorophyll) breaks down and the orange-yellow (beta-carotene) and red (lycopene) pigments increase. The concentrations of orange-yellow and red pigments determine the color of a ripe tomato.
Pick ripe fruit as soon as they ripen so that the plant continues to produce new tomatoes. This is very important at the end of the season when you want the plant to concentrate on swelling and ripening the remaining fruits.
Remove yellowing leaves from plants towards the end of the season to allow more sunlight to reach the fruit and ripen them.
Tomato Ripening Tip
As the season comes to and end there are a few tips and tricks to keep in mind to get the most from your tomato harvest:
- Tomatoes ripen from the inside out. To know a tomato is ripe let the skin turn red (if the variety is a red one) and you will know the fruit is ripe. (If the variety you planted is supposed to be green at harvest, you must keep track of the days from transplanting to know the harvest time.)
- The red color of a tomato will not form when the temperatures are above 86°F. If the summer is very hot where you live, leaving fruit on the vine may cause them to look yellowish-orange rather than red. Red pigment won’t form if temperatures exceed 85°F. If the weather is very hot, it’s better to pick at the pink stage and let the tomato ripen indoors in cooler temperatures.
- Tomatoes to do not need light to ripen once they are off the vine. Do not put picked tomatoes in a sunny window to ripen—they will only overheat or burn and ripen unevenly before they redden and spoil. Put picked tomatoes in a dark place away from a window where the temperatures are 65 to 70°F.
- To make picked tomatoes redden up faster put them into a paper bag with an apple or a banana. Ethylene gas given off by an apple or banana will speed the tomato ripening process.
- Do not store partially ripened tomatoes in the refrigerator. Very cool temperatures will stop the ripening process. Allow picked tomatoes to ripen shoulders up in a dark place at room temperature.
- Fully ripened tomatoes keep their best flavor when they are stored at room temperature, but they will last only a day or two. If you need to keep them longer than that and they are small enough, put them into the butter compartment of the refrigerator–the warmest part.
- When picked at the peak of ripeness, canned or frozen tomatoes retain their flavor and nutrients better than almost any other vegetable.
- About a month before you expect the first frost, start plucking all new flowers off of your tomato plant. That will direct the plant’s energy into ripening the tomatoes that are already on the vine instead of producing new ones that won’t have time to mature.
- If you have an abundance of green tomatoes at the end of the season, you can wrap each one separately in newspaper then place them loosely in a single layer in a cardboard box so they don’t squash each other. Keep them in cool, dry place until they ripen.
- If you have unripened cherry tomatoes on the vine when frost comes, you can cut off an entire truss and hang it in the kitchen or garage until the fruit ripens and is ready for harvest.