http://bit.ly/tomatosplitting
Why do tomatoes split and crack? Usually it's caused by a lack of water during the extreme temperatures of the summer sun.
Prevent your tomatoes from splitting and cracking during the hot summer months by following some simple steps.
It's important to note that many people don't know that split tomatoes can harbor a wealth of bacteria that can kill the tomato plant. So if you happen to notice a split tomato still on the vine... pull it off and if it's ripe, eat it. Cut around the cracked area and use like you would any other tomato.
The most important thing to remember is to not let the plant dry out. Water on a consistent schedule.
Use compost instead of fertilizer and put mulch around the plants as this allows proper drainage and airflow.
Remember if it's extremely hot tomatoes like some shade just like humans.