It's a common problem: Brenda Rees of Eagle Rock writes that her pomegranate tree, about 5 years old, delivers loads of fruit, but much of it has been splitting open this year. She asks: "Have I been overwatering it?"
The answer comes from Yvonne Savio, manager of the UC Cooperative Extension's Common Ground Garden Program for Los Angeles County, who oversees the related training of master gardeners.
Fruit skin that splits — also somewhat common with oranges — is due to relatively irregular watering. If a dry spell (no rain or no watering) is followed by a sudden influx of water, the cells inside the fruit expand faster than the skin cells. Because the skin cells don't expand as rapidly, they get pulled apart, resulting in the split.
The solution is to water more moderately and more frequently, so the skin can grow continuously and keep up with the expanding interior of the fruit.