Why Are My Tomatoes Splitting?

Splitting tomatoes are nearly always a watering problem, not a disease. The fruit dries out, then gets a big drink all at once, swells fast — and the skin cracks because it can't keep up. Sort out your watering routine and the cracking stops.

Why it happens

A tomato grows from the inside out. When the plant is short of water, the fruit's growth slows and the skin firms up. Then a heavy watering (or a summer downpour after a dry week) floods the plant, the flesh swells quickly, and the now-inflexible skin tears.

You'll see two patterns:

• Concentric cracks — rings around the stem end, usually after a sudden glut of water.
• Radial cracks — splits running down from the top, common in a hot spell followed by rain or a big soak.

Either way, the trigger is the same: dry, then flooded. Pots and growbags split most because they dry out fastest. A spell of warm UK weather, a missed day or two, then a soaking — and you've got cracks. Some thin-skinned varieties (especially cherry tomatoes) are simply more prone to it.

The fix

The cure is consistency. You're aiming for soil that stays evenly moist, never bone-dry and never waterlogged.

Water little and often, on a routine. In a warm UK summer, plants in pots and growbags often need watering once a day — sometimes twice in a heatwave. Don't let them wilt and then drown them to make up for it. Our guide to watering and feeding tomatoes walks through the steady routine in full.

Mulch to even out moisture. A layer of mulch — compost, grass clippings or bark — over the soil surface slows evaporation and smooths out the wet-dry swings that cause splitting. It makes a real difference for plants in the ground.

Pick split fruit promptly. A cracked tomato won't heal. Pick it straight away, before the open skin lets in rot or attracts fruit flies, and use it in cooking — a split tomato is perfectly good for sauces, soups and roasting.

Prevention

Steady watering is the whole game. Build a habit and the problem disappears.

• Keep it regular. Same time each day in summer for pots and growbags. Push a finger into the compost — if the top 2–3cm is drying, water.
• Don't over-correct. If a plant has dried out, rewet it gradually over a day rather than emptying a full can on it in one go.
• Mulch the surface to hold moisture between waterings, especially in beds and large containers.
• Use bigger containers. A 30-litre-plus pot or two plants per growbag dries out far more slowly than a small pot, so moisture stays steady.
• Pick at the first blush of colour in a hot, changeable spell. Tomatoes ripen happily indoors on a windowsill, and fruit off the plant can't split.

A few cracks here and there are normal and nothing to worry about — the tomatoes are still fine to eat. It's a sign to tighten the watering routine, not to panic.

For the full growing routine from sowing to harvest, see our main guide to growing tomatoes in the UK. And if your fruit is staying stubbornly green, that's a different issue — see why tomatoes won't ripen.

PS — Split fruit isn't a failure. It just means your plants got thirsty, then thirsty no more. Even out the watering and you're done.