Tomatoes split because their skin becomes too weak to contain the pressure inside the fruit. This often happens when there are abrupt changes in watering—such as after a dry period followed by heavy rain or excessive irrigation. The tomato absorbs water rapidly, causing it to swell quickly, but the skin cannot stretch fast enough to accommodate this sudden growth, leading to splitting or cracking. This is especially common in large or thin-skinned varieties like heirlooms. The splits can be vertical (top to bottom) or horizontal (around the fruit). While split tomatoes are typically still edible, the cracks can allow rotting or disease if not harvested promptly. To prevent splitting, it is advised to maintain consistent watering, use mulch to retain soil moisture, and pick tomatoes as soon as they ripen.