Why Do My Tomatoes Split?
Tomatoes usually split after the fruit suddenly takes up more water than its skin can stretch to hold. The familiar trigger is drought followed by heavy rain or generous watering. Cracked fruit is frustrating but often still usable, provided it is harvested promptly and has not begun to rot.
Check the type of split first. Circular cracks around the stem are common after sudden moisture changes, while long vertical splits often develop as fruit expands quickly in warm weather. Pick cracked tomatoes as soon as they are ripe enough to use, because open skin admits mould and rot. If the crack is shallow, clean and dry, cut around it and use the fruit promptly in cooking or salads. Discard fruit that is soft, leaking, mouldy or smells unpleasant. Do not leave split fruit on the truss hoping it will heal; it will not, and it can attract pests or encourage decay close to healthy tomatoes.
The main prevention is steady soil moisture. During dry periods, check outdoor tomatoes every morning and water the root area deeply when the soil 5 cm down is beginning to dry. Avoid alternating days of severe dryness with a large soaking. In pots and grow bags, water slowly in two passes a few minutes apart, allowing compost to absorb it instead of sending water straight through drainage holes. A water butt is useful, as rainwater is usually close to outdoor temperatures and readily available during dry spells. In very hot weather, check containers again late afternoon, but water only if they are genuinely drying, not merely warm on the surface.
Mulch plants once the soil has warmed in late spring or early summer. Spread 3 to 5 cm of garden compost, leaf mould or clean grass clippings around outdoor tomatoes, keeping it clear of stems. Mulch reduces evaporation and softens the impact of a sudden shower after dry weather. In greenhouse borders, use garden compost as a surface mulch and make sure irrigation reaches the full root zone. For pots, a thin layer of compost or fine bark can help, although regular checking remains essential. Avoid compacting soil by repeatedly walking beside plants, as compacted ground sheds rain rather than absorbing it evenly around roots.
Protect roots from extremes rather than trying to control every shower. Where persistent summer rain is forecast, move container tomatoes under a sheltered greenhouse overhang, porch or temporary cover if they can still receive good light and ventilation. Do not seal plants into a humid space, as stale air encourages disease. Outdoor plants in beds cannot be kept fully dry, but a well-mulched, well-structured soil absorbs rain more gradually. Improve heavy ground each year with garden compost and avoid digging when it is wet. Raised beds can help where drainage is consistently poor, while containers need clear holes and no permanently water-filled saucers.
Choose varieties and cultivation methods with cracking in mind. Thin-skinned, very large and heavily ribbed tomatoes tend to be more prone to splitting than smaller, firmer varieties. This is not a failure of your care, because weather swings vary greatly between gardens. Pick fruit as soon as it has reached its expected colour rather than leaving it overripe on the vine. In a greenhouse, harvest regularly during hot spells, when growth can be fast. Give each plant enough root space and avoid sudden increases in feed strength, which can promote rapid soft growth. Label varieties that cope well on your plot for future sowing or buying.
After a cracking episode, do not stop watering in an attempt to toughen fruit. Continue a measured, consistent routine and remove damaged fruit before rot spreads. Check your compost depth, drainage and container size, then make one or two useful changes rather than constantly changing everything. A newly planted tomato may need more frequent checks until roots fill its space, while an established bed plant benefits most from mulch. In cooler northern gardens, rain can be the bigger challenge; in warmer sheltered southern sites, drought may start the cycle. Keep notes on weather and variety, as they are often the clearest guide for next season.
Frequently asked questions
Can I eat cracked tomatoes?
Yes, if the crack is clean, shallow and the fruit is otherwise firm and sound. Harvest it promptly, wash it, cut away the damaged section and use it soon. Do not eat tomatoes that have mould, soft rot, leakage or an unpleasant smell, because microbes can enter through open skin.
Does too much rain split tomatoes?
Heavy rain is most likely to cause splitting when it follows dry soil. Roots take up water quickly, the fruit swells and the skin ruptures. Mulching, improving soil structure and keeping moisture more even during dry weather all reduce the sudden change that leads to cracks.
Will feeding prevent tomato splitting?
Feeding is not the main answer. Cracking is chiefly caused by uneven water supply, although excessive feeding can encourage rapid growth. Use fertiliser only at the label rate once plants are fruiting, and concentrate on consistent watering, mulch and prompt harvesting of ripe tomatoes.
General guidance for UK home gardens and allotments. Conditions vary by region, soil and season; the RHS or a local garden centre can give site-specific advice. Page updated 19 Sep 2026.