As temperatures drop and the threat of frost looms for gardeners in USDA Zones 3 through 9, your late-season tomato plants often hold a final bounty of unripe fruit. You can easily extend your harvest by bringing these green tomatoes indoors to finish ripening safely away from the cold. Understanding the physiological stages of the fruit allows you to identify which tomatoes will ripen successfully and which are better suited for culinary use as green tomatoes.
Identifying Ripening Candidates
Look for fruit that has reached the breaker stage, where the color is just beginning to shift from deep green to a pale, whitish-green or slight blush. These tomatoes have already received the necessary signals from the plant to complete the ripening process. If the fruit remains a hard, dark green, it likely hasn't developed enough to ripen off the vine and may remain bitter or starchy.
Optimal Indoor Conditions
To encourage ripening, place your tomatoes in a single layer on a tray, ensuring they are not touching. Store them in a cool, dark location, ideally between 60°F and 70°F. Sunlight is not required for ripening—in fact, it can cause the fruit to overheat and soften unevenly. Check your stash every two days, removing any fruit that shows signs of decay to prevent the spread of mold or rot to healthy tomatoes.
For faster ripening, place a single ripe banana in a paper bag with your green tomatoes; the ethylene gas emitted by the banana acts as a natural ripening catalyst for the fruit.
Storage Strategies
If you prefer to delay the process, you can hold tomatoes at a slightly cooler temperature, around 55°F, which slows the respiration rate. Avoid placing your tomatoes in the refrigerator, as temperatures below 50°F will destroy the cell walls, resulting in a mealy, flavorless texture. For those fruit that never ripen, embrace the tangy crunch of fried green tomatoes or incorporate them into a zesty late-season chutney.
Preparing for the First Frost
When the forecast predicts a hard freeze, harvest all remaining fruit regardless of size. Clean them gently with a damp cloth, dry thoroughly, and inspect for any bruising. Keeping your harvested tomatoes stored away from direct heat sources like radiators will ensure they stay firm and flavorful for as long as possible.