How do you stop tomatoes from rotting on the vine?

Last year I had many tomatoes growing on the vine that started to rot before they became fully ripe. How do I stop that from happening this year?

How do you stop tomatoes from rotting on the vine?
Are the bottoms rotting? That is blossom end-rot. That is due to calcium deficiency. You can get sprays that will prevent that, and then add some lime to your garden.
Reply:It sounds like your soil was retaining too much moisture? or the tomatoes were close to the ground. Make sure the tomatoes are staked up. good air circulation should let the tomatoes ripen naturally on the vine assuming you have no other diseases on the plants.
Reply:If they are rotting from the bottom up, then you have blossom end rot and that means you have a calcium deficiency in your soil. This can be cured easily both with a spray that is available. Just spray the plant with it and the new tomatoes will nto be rotting. When you plant them, put some lime into your garden, I recommend the pelletized lime since the powder takes 90 days to get into the mix.
Reply:Pick them when they are green or turning ripe and set them on a table outside out of the sun and give them to your friends or neighbors! That`s alot better then seeing them go to rot!!!!
Reply:I read the few answers. I'm leaning towards the "too much moisture". Blossom end rot is another possibility as is sun scalding. You should not water the plants directly, just the soil beneath and in the morning so any splash can evaporate off of the plants.
Reply:pick them and sell them.