Cooler fall temperatures, shorter days and longer nights stall tomato ripening. Right now my tomato plants hang heavy with green fruit. Each day I check for signs of ripening, but see no pink progress. November is just around the corner and the almanac warns of impending frost. It’s time to harvest those tomato hold-outs and ripen indoors.
Lycopene and carotene pigments give tomatoes their signature red color. The pigments require temperatures between 70-80 degrees Fahrenheit to develop. Temperatures below 70 degrees keep tomatoes green. Temperatures above 80 degrees cause red tomato varieties to turn yellow or orange instead.
It ain’t easy being green
If you’ve ever tried to ripen tomatoes indoors, you’ve probably noticed that a few stubborn tomatoes refuse to turn. Dark green tomatoes that are small and very hard are immature green tomatoes. They never reach their full potential; time only turns them dull and tasteless.
Mature green tomatoes are full size and pale-green in color, with an inside texture that looks like jelly. Tomatoes in this stage taste tangy. They are delicious to eat as fried green tomatoes. Mature green tomatoes can be fully ripened indoors.
To ensure tomatoes reach green maturity, wait as long as possible to harvest before first frost.
How to ripen green tomatoes indoors
Step 1: Harvest green tomatoes. Save only mature green fruit to ripen indoors. Discard immature green and damaged fruit to compost.
Step 2: Line a cardboard box with newspaper. Place green tomatoes in the box, leaving a little space between each fruit for air circulation. Cover tomatoes with a layer of newspaper, and repeat up to three layers. Top the last layer of tomatoes with newspaper and close box.
Step 3: Store the box at 70-80 degrees Fahrenheit to ripen tomatoes in about two weeks. Adding bananas to the box will turn your tomatoes red quicker because the natural ethylene in bananas speeds up the ripening process.
If you want to ripen small lots of tomatoes over time, prepare three boxes as described above. Keep one box at 70-80 degrees Fahrenheit, the second at 60-70 degrees, and the third at 50-60 degrees. Move the boxes to warmer temperatures in succession to steadily ripen your tomatoes. I was able to eat garden fresh tomatoes in January using this method!
