The first heavy frost will kill tomato plants in the garden and ruin the fruit that is to them. A lot of the green fruit can be saved to ripen indoors. Pick it when frost is threatened and store it.
Best results will come from mature green tomatoes (greenish white on the blossom end) and those showing a faint blush of pink color. They will ripen in about two weeks if stored at 65 to 70 degrees or in about three weeks at 57 degrees.
Ripe tomatoes can be held in the refrigerator for nearly a week. But if tomatoes are put into the refrigerator before ripening, they will never ripen properly. Tomatoes stored in the refrigerator for more than a week may lose their characteristic flavor and develop a flat taste.
A tomato passes through various stages of coloration before becoming red-ripe. As it matures, it changes color, texture and flavor.
When it is about as large as it is going to get, the blossom end starts changing from dark green to pale whitish-green (the mature green stage). The next stage is when the tomato is just beginning to turn pink. A pink tomato is one where one-half at the blossom end has turned pink.
Green tomatoes that have not reached the mature green stage probably are not worth trying to save unless you want to use them for relishes. It is possible to get them to develop some color but the flavor is insipid and the texture of the flesh soft and spongy.
Light is not essential for the development of red color. Mature green tomatoes may be stored in total darkness and ripen satisfactorily. The rate the tomatoes receive some light.
Light will increase color somewhat, of ripening increases somewhat when but when tomatoes are placed in direct sunlight, the added heat often reduces their quality. Tomatoes in sunlight lose extra water and shrivel.
The buildup of temperature causes breakdown of cells.
Damage to tomatoes from freezing depends on the duration of temperature at or below the freezing point. Research has shown that leaves of tomato plans in the field or garden freeze at about 30.2 degrees F., stems at about 30.0 and fruit, either on or off the plant, at about 30.5 degrees.
One of the symptoms of slight and moderate freezing injury is a yellowish color that develops over the damaged area. This color change seems to be induced by sunshine and usually is apparent in one or two days.
Tomatoes also may be damaged by low but non-freezing temperatures, such as an average daily mean temperature below 50 degrees for a week.
Mature green tomatoes that have been exposed to chilling temperatures (below 40) for three or four nights before harvesting may fail to ripen properly and may not quickly.
On the other hand, tomatoes that have been hit by a single light frost may not be badly damaged if the following day is not very cold.
Since light is not necessary for red color, the tomatoes can be wrapped in paper during the ripening process. The main advantage of such wrapping is reduction of bruising and decay and maintenance of a more uniform temperature.