How to Ripen Green Tomatoes Indoors
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Knowing how to ripen green tomatoes indoors is useful when a frost arrives before the fruit has turned color. Extension programs in Iowa and Colorado give practical guidance on which fruit to pick, where to keep it, and what conditions help it change color. This article covers those recommendations, the points where the sources give specific numbers, and the questions they leave unanswered.
Quick answer
- Pick fruit that is nearly full size, has a glossy green look, and has no blemishes, according to Colorado State University Extension.
- Store wrapped tomatoes in a cool, dark place at about 60 to 65 degrees Fahrenheit, as Iowa State University Extension advises.
- Once the fruit begins to color, move it to room temperature, according to Colorado State.
- Check the fruit regularly for rot, and remove any tomato that is soft or spoiling.
Why green tomatoes need to be picked with care
A green tomato will ripen only if it is mature enough when picked. Fruit that is too small or too immature may stay green or ripen with poor flavor and texture. Extension guidance therefore starts with the choice of fruit, not with the storage container. The Colorado State publication, which is written for home gardeners, makes that point directly, and the Iowa State answer makes a similar point in the context of a frost warning.
Indoor ripening is not a replacement for a full season on the vine. The sources describe it as a way to finish fruit that is nearly ready when weather turns cold. Fruit picked too early is not expected to develop the same quality as fruit left on the plant, so the best results come from choosing well at harvest.
Step one: choose the right fruit
Colorado State University Extension recommends picking ripening fruit and green tomatoes that have a glossy green appearance and have reached at least three-fourths of their full size. The fruit should also be free of blemishes and should have the stem removed before storage. Those criteria give a practical check at harvest time, and they help separate fruit that is likely to ripen well from fruit that may not.
Iowa State University Extension gives a related rule. It advises harvesting fruit that is nearly full size or mature before a frost hits. The advice matches the Colorado State criteria, and together the two sources point to picking fruit that is close to its final size but has not yet begun to show a red color. That is the stage in which the fruit has the best chance of ripening indoors.
Step two: prepare the fruit
Colorado State advises removing the stems, washing the fruit, and letting it air dry before storage. Drying matters because surface water can encourage problems during storage. Handle the fruit gently at every stage, since bruised tomatoes are more likely to rot before they ripen.
Iowa State suggests wrapping each tomato in newspaper. The paper keeps the fruit separated and helps it hold a stable environment during storage. Wrapping also makes it easier to check each tomato without disturbing the others. Choose unprinted or plain newsprint where possible, although the sources do not specifically address ink.
Step three: keep the fruit cool and dark
Iowa State University Extension recommends storing wrapped tomatoes in a cool, dark location at about 60 to 65 degrees Fahrenheit. The source gives examples such as a basement or cellar. A cool, dark place slows the ripening process so that fruit can change color gradually and be checked over time. Temperatures much warmer than this range are likely to speed ripening, while much colder temperatures may slow it.
Oklahoma State University Extension has made related points about temperature in other publications, but the page could not be retrieved for this article, so this guide does not rely on it. The temperature range above comes from the Iowa State source alone.
Step four: move the fruit to room temperature
Colorado State University Extension says that fruit does not need light to ripen. It also advises that, once tomatoes start to color, they should be moved to room temperature. The reasoning is that ripening proceeds faster at room temperature, and the color change becomes easier to observe. Check the fruit daily once it begins to change, because the transition can be quick.
Some people place ripening tomatoes in a single layer so that they do not touch. This is a common practical step, but the sources reviewed here do not specifically require it. If you use a shallow tray, keep the fruit separated so bruising and rot do not spread from one tomato to the next.
Humidity and shriveling
Colorado State notes that low humidity can cause fruit to shrivel, and it describes humidity control as a common challenge when ripening indoors. Heated rooms are often dry, which can make tomatoes lose moisture faster. The source does not give a specific humidity target, so this article does not recommend one.
A practical response is to watch for wrinkling skin and to avoid leaving fruit in a spot with strong airflow or direct heat. Those steps are general good practice rather than specific advice from the Colorado State page, so treat them as common-sense checks rather than requirements.
Refrigerator and what to avoid
Neither source in this article recommends storing green tomatoes in the refrigerator to ripen them. The Iowa State guidance points toward a cool, dark place rather than a cold one, and the temperature range it gives sits well above typical refrigerator settings. This article does not make a claim about refrigerator storage for green tomatoes, because the reviewed sources do not address it directly.
Fruit that is soft, moldy, or showing rot should be removed from the group and discarded rather than kept for ripening. Spoiled fruit can affect the tomatoes around it, so checking the group regularly is part of the method.
How long ripening takes
The reviewed sources do not give a single time to ripen green tomatoes indoors. The time depends on how mature the fruit was when picked, the temperature, and the humidity. Plan for a period of days to weeks rather than a fixed date, and check the fruit at regular intervals. Fruit that has not begun to color after a reasonable period may not ripen well, and it is better to use it in a cooked dish than to wait indefinitely.
Frequently asked questions
When should I pick green tomatoes to ripen indoors?
Colorado State University Extension recommends picking fruit that has reached at least three-fourths of its full size and has a glossy green appearance, with no blemishes. Iowa State advises harvesting fruit that is nearly full size or mature before a frost.
What temperature is best for ripening green tomatoes?
Iowa State University Extension recommends a cool, dark location around 60 to 65 degrees Fahrenheit for storing wrapped tomatoes. Once the fruit begins to color, Colorado State advises moving it to room temperature.
Should I wrap green tomatoes in newspaper?
Iowa State University Extension suggests wrapping each tomato in newspaper. Plain newsprint is a reasonable choice, though the source does not address ink.
Do green tomatoes need light to ripen?
Colorado State University Extension says the fruit does not need light to ripen.
What if the tomatoes shrivel while ripening?
Colorado State notes that low humidity can make fruit shrivel. The source does not give a humidity target, so keep fruit away from strong heat or airflow and check it regularly.
How we chose
This guide uses two university extension publications because they give specific picking and storage guidance for home gardeners. Commercial articles and gardening blogs were not used as sources, because their claims could not be traced to a verifiable publication. Both sources were opened on 2026-10-27, and the quotations above were checked against the text retrieved from each page.
For more on the crop, see how to grow tomatoes from seed to harvest, and for preserving a harvest that is not eaten fresh, see how to preserve tomatoes.
What we could not verify
The two extension sources agree on picking fruit that is near full size and on keeping it out of direct heat, but they do not give the same level of detail. Iowa State gives a specific temperature range, while Colorado State gives picking criteria and a humidity note. The sources also do not give a ripening time, so the timing in this article is an estimate that depends on the conditions in the room.
What the sources do not say
The reviewed sources do not state a refrigerator temperature or a specific humidity target, do not give a ripening time, and do not describe the effect of bagging several fruits together. They also do not address ink on newspaper. Readers should treat the temperature range as the one number provided by the sources and check fruit regularly rather than relying on a set schedule.
Sources
- Iowa State University Extension and Outreach, Yard and Garden, Can I ripen green tomatoes indoors before frost?, https://yardandgarden.extension.iastate.edu/faq/can-i-ripen-green-tomatoes-indoors-frost (opened 2026-10-27). Quoted: “Store wrapped tomatoes in a cool (60 to 65 degrees Fahrenheit), dark location, such as a basement or cellar.”
- Colorado State University Extension, PlantTalk Colorado, Ripening Tomatoes Indoors, https://planttalk.colostate.edu/?p=2475 (opened 2026-10-27). Quoted: “Pick ripening fruit and green tomatoes with a glossy green appearance that have reached at least three-fourths of their full size and remove stems.”
