Find yourself with more green tomatoes than ripe ones right now? Getting tomatoes to ripen on the vine this late in the season comes down to three things: pruning, picking and protecting. Begin by removing any dead, diseased or damaged stems and leaves. Plant pruning will help redirect energy towards ripening existing fruit.
Root pruning will also encourage ripening. To root prune, simple stick a shovel or trowel six to eight inches deep into the ground, all the way around your tomato plant. This will chop off the ends of the roots and force the plant to stop new growth. With those root ends clipped off the tomato plant goes into fruit production mode. It should be noted that root pruning will dramatically decrease the life of your plant.
Pick off flowers, small fruit and any tomatoes that are soft to the touch or showing signs of disease. If your vines are loaded, pick a few and bring them inside to ripen. Removing excess fruit will encourage the remaining tomatoes to ripen.
Protect your plants at night by covering them with an insulating material. Tomatoes need more than sixty degrees of temperature to ripen properly. With nighttime temperatures dropping into the fifties, keeping your plants warm will keep fruit ripening. Prune, pick, protect; three things you can do to speed up the vine-ripening process. If it gets too late in the season, you can always pick the just-ripening fruit and bring your harvest indoors to finish the ripening process.