How to Ripen Green Tomatoes

Few fruits are more versatile and delicious than tomatoes, but knowing when they're ripe and ready to eat can be tricky. Eating tomatoes before they're ripe means you don't get the full taste and flavor benefits, but allowing them to ripen on the vine means animals or bugs may get to enjoy them before you do.

Fortunately, it's possible to ripen green tomatoes after you've plucked them from the vine. "Many people choose to after-ripen tomatoes indoors," says Daniel Cunningham, a horticulturist at Texas A&M AgriLife. "Not only does this practice prevent predation from wildlife and reduce exposure to extreme weather conditions, but it also might help give you more control and could even speed up the ripening process."

Harvesting Green Tomatoes

You'll recognize underripe tomatoes by their color. "Tomatoes that are green are usually not yet ripe," says Christopher Landercasper, director of farming operations for the Sonoma's Best Hospitality Group. "All tomatoes are green before they turn red, purple, or yellow, or some other color or combination."

Harvest All Green Tomatoes at the End of the Season

If you live in a region with cold weather extremes, Cunningham suggests harvesting all of the tomato fruits on the plants before the end of fall so they can after-ripen safely indoors. "Green tomatoes left on the vines during a freeze often succumb to the frost and become inedible," he says. "Harvest them when the fruit begins to change color and soften to the feel. At this point, most of the carbohydrates and sugars that will be sent to the fruit are already present in some form, but after-ripening indoors will enhance the flavor."

Don't Harvest Too-Small Green Tomatoes

When harvested while still immature, green tomatoes may rot before they have a chance to become ripe. "There is a fairly good way to tell which tomatoes have developed enough to further ripen," Landercasper says. "Take an average sized tomato and cut it in half. If the gelatin holding the seeds is liquid enough that when you cut through the tomato, the seeds move, then tomatoes of that size and larger will ripen. However, if your knife cuts the seeds in half because the gelatin around the seeds is not liquid enough to allow the seeds to move away from the knife blade, then it will most likely rot before ripening."

Separate Ripened and Unripened Tomatoes

Depending on the type of tomato and when it was picked, some varieties might ripen in a few days, while others could take up to two weeks or more. "Check on your tomatoes frequently and remove those that have fully ripened," Cunningham says. "Also, if at any time through the after-ripening process you notice a mushy fruit or tomato with a bad spot, quickly remove and discard."

Ripening Green Tomatoes

Ripening is a natural process, so by placing your tomatoes in the proper environment, they'll continue to ripen without any hands-on work from you—but here are a few ways to get the best results.

Hang the Entire Tomato Plant Indoors

Tomatoes that ripen on a vine taste better than ones that don't. Instead of harvesting your tomatoes at the end of the season, dig up the entire plant (which will die anyway), hang it in a cool, dry spot that receives some light indoors (avoid overly sunny spots), and let the fruits color up on the vine.

Leave Tomatoes on the Counter

While experts say refrigerating ripe tomatoes can ruin their taste, it also halts the ripening process. If you've brought slightly under-ripe tomatoes home from the farmers market or inside from your garden, leaving them on the counter will allow them to slowly ripen on their own. Store them at room temperature with the stem intact and the stem's side facing down.

Put Tomatoes in a Paper Sack

Tomatoes and other ripening fruits, such as bananas, apples, and avocados, rely on ethylene gas—not sunlight—to ripen, so keeping green tomatoes in a confined, temperature-controlled area once they're harvested will speed up the process. "Choose a confined spot, such as a paper sack or a cardboard box, that stays roughly around the 70 to 75 [degrees Fahrenheit] range," Cunningham says. "This will allow for better airflow and less humidity, so a better concentration of natural ethylene gas can hang around."

Add Another Ripe Fruit

Since other fruits release ethylene gas as they ripen, exposing a green tomato to another ripening fruit will help it mature faster. "If you need a tomato to ripen more quickly, put it in a paper bag with a ripe banana," Landercasper says. "The ripe banana will emit ethylene gas, and it will concentrate in the air in the bag, helping to speed the ripening of your tomato." If you don't have a banana on hand, an apple will also work, Cunningham says.