Save Green Tomatoes Before the Frost: Ripen Indoors and Use the Rest

Why the first frost decides the harvest

Every tomato grower ends up here eventually. The garden still looks full in late September, but the forecast is calling for frost, and the vines are covered with fruit that has not turned red yet. A single hard frost turns firm green tomatoes into soft, waterlogged mush, and all that potential goes to waste overnight.

You do not have to lose them. With a little forethought on frost night, you can bring most of that fruit inside and watch it ripen over the coming weeks. And for the ones that never do color up, there are solid, tasty ways to use them anyway.

The plan has three parts: pick the right fruit, ripen the good ones indoors, and put the rest to work in the kitchen. None of it is complicated, and all of it keeps food out of the compost bin.

Pick the right fruit, and pick it gently

Go out the day before a forecast frost, not the morning after. Frost damage shows up as soft, water-soaked spots that will spoil in storage, so harvesting in advance matters.

When you pick, sort by maturity and condition:

• Save the mature fruit. The tomatoes most likely to ripen indoors are the ones that have turned from deep green to a lighter, greenish white. These are "mature green" tomatoes. Small, hard, dark green fruit is less likely to color up.
• Pick only fruit that is solid, firm, and free of cracks, soft spots, and insect damage. A damaged tomato will rot in the box and can take the ones next to it down too.
• Leave the stems on or off, your choice, but remove any leaves. Clean the fruit and dry it well before storing, since surface moisture invites mold.
• Check for frost damage after picking. Any fruit with dull, water-soaked, or bruised patches should be set aside and used quickly, not stored.

The small varieties, like cherry and grape tomatoes, are a different case. They rarely ripen well indoors, so plan to preserve those instead of waiting on them.

Let them ripen in a cool, dark spot

Green tomatoes ripen fine indoors if you give them the right conditions. The goal is to slow them down so they color gradually over weeks instead of turning all at once.

The standard method:

• Wrap each tomato loosely in a single sheet of newspaper. Individual wrapping keeps rot from spreading between fruit.
• Set the wrapped fruit in a single layer in a box or on a shelf. Do not pile them deep, that traps moisture and speeds spoilage.
• Keep them in a cool, dark place around 60 to 65 degrees Fahrenheit, such as a basement or cellar.
• Check them every few days. Pull out and use or discard any fruit that is softening, molding, or showing damage before it can affect the rest.
• When a tomato starts to show color, unwrap it and bring it to room temperature. It will finish ripening in a few days.

One warning worth repeating: a tomato that has been frozen will not ripen properly. If frost does sneak in, pick anyway, but expect to cook those rather than store them.

A quicker trick for the ones in a hurry

If you want a few tomatoes for this week rather than next month, use the ethylene trick. Ripe fruit gives off ethylene gas, which is what triggers ripening.

Place a handful of green tomatoes in a paper bag with an apple or a banana, close it loosely, and leave it at room temperature. The gas from the apple or banana speeds up color change. Check daily, because they can go quickly once they start, and move any colored fruit out before it gets overripe.

This works best with tomatoes that were already close to mature. It will not save tiny, hard green fruit, so do not expect miracles from the little ones.

What to do with the green ones that will not ripen

Not every tomato is going to turn red, and that is fine. Green tomatoes are a perfectly good ingredient in their own right, with a firm texture and a tangy, tart flavor that holds its own in the kitchen.

A quick note on safety, because green tomatoes come up in questions a lot. Green tomatoes contain compounds called glycoalkaloids (tomatine is the main one), which are more concentrated in immature fruit and drop as the tomato ripens. In normal cooking amounts, green tomatoes are a long-established food. Cooking them reduces any potential concern, so the classic uses are all cooked. The main thing to remember is not to eat a huge quantity of raw green tomatoes, and to cook them in the usual ways. As with any produce, skip anything bruised, damaged, or showing signs of decay.

Practical ways to use them that will not ripen:

• Fried green tomatoes. Slice firm green fruit, coat in cornmeal, and pan fry until golden. The firm texture is exactly what makes them work.
• Green tomato salsa. Dice green tomatoes with onion, jalapeño, garlic, and cilantro, add lime and salt, and pulse. They hold a crunch instead of turning to mush.
• Green tomato chutney or relish. Simmer chopped green tomatoes with onion, vinegar, sugar, and spices. It keeps well and pairs with meats and cheeses.
• Pickled green tomatoes. A vinegar brine turns them into a tart, crunchy pickle for the pantry.
• Cooked into sauces or soups. When nothing else appeals, they cook down fine into a sauce or soup base, even though they will not have the sweetness of sun-ripened fruit.

What to do with the ones that already froze

If frost catches you off guard, all is not lost. Softened, frozen fruit will not ripen or store, but it is still good for cooking. Pull off the worst of the mushy skin and cook the rest into sauce, salsa, or chutney soon after. Food that has been through a frost is not a candidate for long storage, so use it within a few days.

A calm end to the season

The first frost does not have to mean the garden's work ends in a pile of mush. With a little sorting and a cool, dark shelf, most of that green harvest keeps paying off through October and into November. And the fruit that never turns red still has plenty of good uses in the kitchen.

That is the neighborly version of a good garden: nothing wasted, everything used, and a little know-how shared for the next time the forecast turns cold.

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— C. Steward 🍅