Tomatoes can split due to fluctuations in the amount of water they receive. When tomatoes grow in drought conditions or have little supplemental water, heavy rain can cause the insides to grow faster than the outer skin, resulting in the tomatoes cracking. The most common cause of tomato splitting is a heavy rain following periods of relatively dry weather. Uneven irrigation can also result in splitting. High humidity, calcium deficiencies, and excess nitrogen in the soil can contribute to fruit cracking as well. Tomato splitting typically occurs in ripening fruit, though green tomatoes can be affected. The split follows one of two patterns: radial cracking and concentric cracking.

To prevent tomato splitting, it is recommended to keep the plants consistently moist to minimize the impact of a sudden rainstorm, as the plants wont suffer the shock of excessive water after ongoing dry conditions. Tomatoes need an inch to 2 inches of water per week, and wide fluctuations of moisture in the soil can cause this kind of damage. Some tomato growers say that quick, extreme changes in temperature, such as going from hot days to cool nights, can also cause rapid growth that leads to cracks and splits.

If tomatoes split, its important to harvest them as quickly as possible, as split tomatoes are much more susceptible to rot and insect damage. While it may be impossible to avoid splitting completely, split tomatoes can still be eaten as long as they dont smell sour, ooze, or show signs of pests or diseases.