I have loads of tomatoes, after they turn red they split open any ideas as to why this happens?

Mr. Doglips-
There are various reasons for this condition and some varieties are more susceptible than others. The single biggest reason is inconsistent water, applied by nature or you. If we have a big rain and it heats up the next day the tomatoes will be prone to cracking. If you let them get too dry and give them a big drink, the same thing might happen. Hot weather brings on cracking. Try to use a lot of finished compost in your garden, which will automatically regulate the water. Compost acts as a regulator to absorb and release water naturally. Try to keep the soil moisture constant, water early in the morning and mulch heavily to maintain the moisture in the roots. By the way, when you cut up the cracked tomatoes in a salad they taste just as good. I think cracked tomatoes are kinda like weeds, we need to learn to live with them.
Tony M.

Tony is right. We have been getting lots of heavy raining and flooding here too. I've been keeping my tomatoes mulched with lots of unfinished compost for extra mulching and soil protection. Plus I'm been using a lot of aerated compost tea loaded with dry molasses, corn meal, seaweed, and Epsom salt in order get a balance of consistent nutrients and fungal disease control on my tomato plants and soil during this crazy weather.

Thanks for the replies, we have had a lot of rain on and off this month and last, I have tried to keep them watered enough and have also used cornmeal, molasses and also been spraying once a week with garrett juice and also spraying with pepper/garlic tea to keep the pests away. I may have to put down some compost. I have a very productive tomatoe crop of 7 plants. The only plant that did not produce at all was the mr.stripey.

Something you can do to reduce the impact of splitting. Pick your tomatoes when they just are starting to turn color and let them ripen on the counter in the house. There will be no difference in taste and you save yourself the risk of damage to the tomato if it remains on the vine, such as cracking, bird strike, hail, worms...

Marlyn

All these suggestions sound great but I'd like to add mine. You might want to try foliar feeding with seaweed. It seems to add some heat resistance and elasticity to the skins so maybe you can get rid of the cracking that way. My tomatoes don't crack, and I travel a lot so sometimes they get inconsistent watering but they get folar feeding with fish/seaweed or liquid Bioform (which has seaweed in it) every other week. I'd say it's worth a shot!

Kathe Kitchens
You mentioned to add seaweed to the foliar feeding will help with the cracking. I add alot of fresh seaweed to my compost, do you think it will help when added to the garden and tilled in? The compost will be added this fall after the plants have died and I start preparing for next year.
The soil is black clay, since this is the first year for a garden at this location. (new house)

Greg,
I'd foliar feed with it right now. It's inexpensive and might just make a big difference. I have seen great improvement in heat & cold resistance on all types of plants from this. Having seaweed in your compost is helpful but I really see the best results from the foliar application. Just a good misting is all it takes, once a week. Are you adding actual seaweed and allowing it to decompose or spraying a liquid or adding powdered? I'm thinking that the beneficial trace minerals might leech out of your compost before you get it in the garden. That would be a waste of your time & money if that were to happen. Just a thought...

I agree foliar feeding is the best and more efficient way to get seaweed to plants.

I make my fish/seaweed compost teas from fish scraps from the local fish market, and seaweed or kelp from the local oriental market.

Kathe Kitchens
I have been foliar feeding once a week with compost tea. The plants are doing real good except the mellons. They are starting to dry up. That's ok. I feel I have gotten a years woth of mellons off of the 5 plants. Besides I and the wife are starting to get tired of mellon almost every day. The sea weed I add to the compost is fresh from Galveston. The last 3 monthly trips, I have picked up 2 bags worth, each trip. I am supprised that sitting in the black bags for up to two weeks at a time, it doesn't stink. But rather it smells real sweet. The dirt, first year garden in this location, is still clay. After 2 - 3 years the clay will turn into nice crumbly soil that the worms just love. Then my garden will be much better.
PS: thanks for the reply.