Typically, tomatoes are left on the vine long enough to ripen before picking. However, sometimes it is necessary to ripen them off the vine. For instance, if there are almost-mature green tomatoes still on the vine when the first frost comes, you can pick them and ripen them inside if you are not going to cover the tomato plants or put them in pots and take them inside for the cold season.
The following methods work best with tomatoes that are almost mature. They should be somewhat soft and have a bit of color near the stem end.
If you try to ripen green tomatoes that are not mature, odds are against it working. Don’t worry, you can still use the immature green tomatoes that don’t ripen in your favorite cooked green tomato recipe. Fried green tomatoes, anyone?
Here’s how to ripen green tomatoes:
Green tomatoes can be placed in a sunny window to ripen. Leave them there until they’ve reached the desired ripeness.
A paper bag can be used to ripen green tomatoes. Put the tomatoes in the bag with a ripe apple or banana and place away from light in a pantry or cupboard. Ethylene gas from the apple or banana will speed up the ripening. Be sure to close the bag up and check on the tomatoes on a daily basis to avoid over-ripening.
If you have a lot of green tomatoes to ripen, you can layer them in a cardboard box with newspaper. You can either wrap each tomato individually with the newspaper and stack 2 layers into the box or place a layer of unwrapped tomatoes down, then a layer of newspaper, and then another layer of tomatoes.
Place the box somewhere away from light like a garage or a closet and check them every few days. Adding a banana to the box will speed up ripening.