According to the book, Root Cellaring: Natural Cold Storage of Fruits & Vegetables, by Nancy Bubel:
"Mature green tomatoes will ripen in 25 to 28 days at 55 degrees."Back just before the first cold frost of autumn, Marlene picked several green tomatoes from our garden, brought them in the house, carefully laid them out on a flat surface in a cool, dry room, with a towel over them. That was weeks ago. The fruits have ripened gradually. Some of the tomatoes develop soft spots or small rotten areas. But those infirmities can be cut out. Then again, many of the tomatoes ripen to picture perfection. Either way, such tomatoes are certainly edible, and a welcome treat long after the garden has died.
The above picture was taken yesterday. It is the end of November and we have several inches of snow on the ground. A storm was howling outside. But we had fresh tomatoes from our garden.
The effort to preserve these tomatoes was minimal. This preservation technique is nothing new. Down-to-earth people have done this with their tomatoes for generations. But I think the idea is worth mentioning every so often for those who have never tried it.