My tomatoes are all rotting on the bottom before ripening. What can I do to prevent them from rotting?

You might as well trash the bad ones and try to get some straw under the other plants and tie them up to stakes to keep them off the ground. You have probably had too much precipitation in your area.

You Need Calcium. Go To Your Nearest Farm Store And Purchase Calcium To Spray On Your Mater Plants. The Problem You Are Describing Sounds Like "blossom End Rot". To Help With This Next Year, Apply 1 Ton Of Lime Per Acre. It Is To Late To Apply The Lime For This Year As It Takes 3 To 4 Months To Get Into The Soil. Blossom End Rot, Will Be At The Bottom End Of The Mater, And Turn Black. If This Is Your Problem, Be Sure To Follow Directions Carefully On The Bottle. Good Luck.