Why Tomatoes Split and How To Prevent It

It often happens after a big rain. And just as you are ready to harvest. You've watched your tomato plants grow and blossom. Nurtured the little green balls into plump, juicy fruits. And as you reach to pluck the ripe red tomato from the vine you notice it–a long crack running across the fleshy skin. Even the most seasoned gardeners have been devastated by a split tomato. Rest assured, there is a simple solution. Read on to learn why tomatoes split and how to prevent it from happening in your garden.

Why Do Tomatoes Split?

The short answer–water. Tomatoes crack or split when rapid changes in water availability cause fruits to expand faster than their skins can stretch. The most common cause of tomato splitting is a heavy rain following periods of relatively dry weather. Although natural rainfall events are typically the culprit, uneven irrigation can also result in splitting. Some studies suggest 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. With radial cracking, a vertical split opens along the side of the fruit. This is the worst type of damage, as the crack exposes the fruit to disease. Tomatoes with radial cracking should be harvested and used as soon as possible, as the fruit will likely rot if left on the vine. Discard any tomatoes that have a sour smell or pus along the crack.

Concentric cracking occurs as a series of rings circling the stem end of the fruit. These rings typically do not expose the flesh of the fruit, reducing the likelihood of disease. Fruits displaying concentric cracking can be allowed to ripen on the vine unless the flesh is exposed. Keep an eye on fruits as they develop.

How To Prevent Tomatoes from Splitting

Tomato plants require a lot of water to ripen fruits, as much as 1 to 2 inches per week. But just as important as how much water the plant receives is the rate at which it receives it. Avoid large fluctuations in soil moisture by providing consistent irrigation, especially during times of drought. It is best to water deeply a few times a week rather than providing small amounts of water daily. You can conserve soil moisture between waterings by applying a layer of compost or organic mulch.

Watch the weather report during periods of drought or dry weather. If soils have been dry or inadequately irrigated, consider harvesting nearly ripe fruit prior to rainstorm events to avoid cracking. You can finish ripening fruits on the counter, though they will not have as much flavor as vine-ripened tomatoes. Another option is to tarp the area where tomatoes grow, collecting the rainwater in buckets for later, more even irrigation. Some serious tomato growers in dry climates grow tomatoes under plastic hoop houses so they can manage irrigation and avoid periodic storms from cracking fruits.

Finally, maintain plant fertility during flowering and fruiting with regular applications of a balanced fertilizer containing calcium. Avoid applying too much nitrogen, which can cause excess foliar growth at the expense of fruits.

While some varieties are marketed as crack resistant, all tomatoes, including cherry and plum varieties, can develop cracks when conditions are right. Careful irrigation practices can help you avoid problems no matter which tomato you grow.