The appearance of splits and cracks on ripening fruit is a common issue for many home gardeners nearing harvest. This physiological disorder occurs when the tomato’s skin cannot accommodate the rapid expansion of the pulp inside. It typically affects fruit nearing maturity and beginning to change color, though green tomatoes can also be susceptible. Understanding the mechanism behind the split allows gardeners to protect their harvest.
The Primary Cause: Inconsistent Water Intake
The direct cause of tomato splitting is a sudden, rapid influx of water into the fruit. This increases the internal pressure, known as turgor pressure, causing the pulp to expand faster than the outer skin (epidermis) can stretch. The skin’s elasticity is the limiting factor. When internal pressure exceeds the skin’s tensile strength, a rupture occurs, usually near the stem end where the skin is least flexible.
This rapid expansion is most often triggered by a significant shift in environmental moisture, such as heavy rainfall following a period of drought. During dry spells, the plant restricts water uptake, and the fruit’s skin hardens as growth slows. When the roots suddenly receive a large volume of water, the plant quickly transports it to the fruit, causing the skin to burst. Temperature fluctuations, like large differences between hot days and cool nights, can also stress the fruit’s skin and compound the issue of inconsistent moisture.
Recognizing Radial and Concentric Cracks
Tomato splitting presents in two primary forms, distinguished by the pattern of the rupture around the stem end. The most severe type is radial cracking, where splits radiate outward from the stem attachment like spokes on a wheel. These cracks are often deep, extending into the flesh, and commonly occur during periods of high heat and humidity coupled with inconsistent watering.
The second type is concentric cracking, which appears as circular or ring-like cracks forming around the shoulder of the fruit. This type is generally less severe than radial cracking and often occurs when fruit is left on the vine too long after reaching full maturity. Concentric cracks can sometimes heal over with a corky, grayish-white layer if shallow, but they still compromise the fruit’s integrity.
Prevention Strategies for Home Gardeners
The most effective strategy for minimizing fruit splitting is maintaining a consistent moisture level in the soil throughout the growing and ripening period. Gardeners should aim for deep, regular watering that keeps the soil evenly moist, rather than allowing it to dry out between infrequent, heavy soakings. Drip irrigation or soaker hoses are excellent tools for delivering a steady, regulated supply of water directly to the root zone.
Applying a thick layer of organic mulch, such as straw or shredded leaves, around the base of the plants is also beneficial. Mulch acts as a buffer, stabilizing soil temperature and reducing surface evaporation. This helps prevent the dramatic moisture swings that trigger the rapid water uptake leading to splitting.
Another proactive measure is selecting tomato varieties bred for greater crack resistance. While no variety is completely immune, cultivars like ‘Celebrity,’ ‘Arkansas Traveler,’ ‘Jasper,’ and ‘Sweet Million’ are known to possess thicker or more elastic skin. Large, thin-skinned heirloom and beefsteak varieties are significantly more susceptible to splitting than smaller, firmer types like Roma or certain cherry tomatoes.
Finally, adjusting harvest timing can save fruit when conditions become unstable. If heavy rainfall is forecasted, harvest any mature or nearly mature fruit, even if slightly green. Tomatoes picked at the mature-green or breaker (first blush of color) stage will continue to ripen indoors without the risk of splitting on the vine during a downpour.
Handling Cracked Tomatoes and Edibility
Once a tomato has split, harvest it immediately to prevent secondary problems from developing. Cracked tomatoes are generally safe to eat, provided they show no signs of decay, mold, or insect infestation. The primary concern is that the split exposes the moist interior, creating an entry point for airborne fungi and bacteria.
If the crack is shallow and the fruit appears clean and firm, simply cut away the damaged portion. Discard the fruit if the crack is deep, oozing, or if the tomato has developed a sour smell. Cracked fruit should be used immediately for sauce, salsa, or juice, as they will not store well and should not be used for home canning due to the risk of microbial contamination.