Posted: 14/09/2013 at 13:41
Guy, ripening is down to temperature. Toms don't need direct sunlight to ripen. Optimum temperatures are low-20sC and above. The lower the temp, the longer they will take.
You need to take overnight temps into account too. If your daytime temps get down to low teens and your overnight temps into single figures, you're better off taking them off the plant and ripening them inside. Put them anywhere warm - remember they don't need sunlight - and safe. And sit them upside down on their shoulders. It minimises the chances to bruising the flesh in contact with a hard surface.
Feeding the toms at this stage won't help them in the slightest. They've done their growing. Ripening is an internal chemical process that happens independently of the plant. Any fertilising you do might aid other, more immature toms on the plant, and, this late in the season, they probably won't make it anyway. Better to save your fertiliser for next season.