It happens every year. There are always some ripe and semi-ripe tomatoes left on the vine that get caught in the first frost of the fall. One of the concerns that people have is whether these tomatoes can be used for canning. The recommendation is not to can tomatoes from frost-killed vines. This may result in an unsafe product because of the potential low acidity of the tomatoes on frost-killed vines.

It's best to pick your tomatoes before the first frost and ripen them indoors. Tomatoes that have turned light green or pink will ripen satisfactorily indoors. Anything greener can be used for frying, relish, salsa, etc. Green tomatoes can be safely canned if you follow the USDA recommendations.

To ripen tomatoes, keep them out of direct sunlight. Room temperature should be between 60 and 70 degrees F. If the temperature falls below 55 degrees F, flavor will suffer. Fruit should be checked daily for decay or rotting. To prevent the spread of decay, the fruit may be wrapped individually in tissue paper. The damaged fruit should be disposed of as soon as it is noticed.

If you did not pick your tomatoes before the first frost, a safe option is to freeze the tomatoes, after cutting away/removing "bad spots" or blemished areas. Tomato juice and stewed tomatoes can be frozen successfully in freezer containers, leaving at least 1-1/2 inch headspace. For the best flavor use these products within 8 to 12 months. Whole tomatoes can be frozen for cooking if you plan on using them within 3 months. The skins may be tough, so it is recommended that you peel the tomatoes and freeze them in freezer containers or freezer bags.

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