Tomato skin splits when the fruit takes up water faster than the skin can stretch to hold it, usually because a dry spell was followed by heavy rain or watering. It looks alarming but it is rarely fatal to the plant. The rest of this page covers how to tell which crack pattern you have, why it happened, what to do with the fruit you’ve already got, and how to stop it on the next truss.
What you are looking at
Look at where the crack sits and which direction it runs before you do anything else. Concentric cracking shows up as rings circling the stem scar, like growth rings on a tree stump, and usually stays shallow. Radial cracking runs in lines from the stem end down toward the blossom end, and these tend to go deeper and split the fruit open further. Both are the same underlying problem, just different directions of stress on the skin.
Check the fruit at different stages. Cracking shows up most on fruit that is turning color or already ripe, because the skin has stopped growing but the inside is still swelling with water and sugar. Green fruit can crack too, but it’s less common and usually means the swing in moisture was severe.
Don’t confuse this with a few other things that show up on tomato skin around the same time of year:
- Catfacing — puckered, scarred blossom end from cool weather during flowering, not a crack at all
- Blossom end rot — a sunken, leathery brown-black patch at the bottom of the fruit, not a split
- Sunscald — a pale, papery patch on the side facing the sun, flat rather than split open
- Insect or bird damage — small, irregular punctures rather than clean lines following the fruit’s shape
If what you’re looking at is a clean line or ring that follows the curve of the fruit and opens the skin without any discoloration around it beforehand, you’re dealing with cracking. That distinction matters because the fix for cracking is entirely different from the fix for blossom end rot, and treating one like the other wastes a season.
What actually causes it
The mechanism, not the myth
The skin of a tomato stretches as the fruit grows, but that stretch has a limit, and the limit drops as the fruit ripens and the flesh softens. When the plant takes up a large amount of water quickly, usually because a stretch of dry soil is followed by rain or a heavy watering, the inside of the fruit swells faster than the skin can expand to match. The skin gives way at its weakest point, which is almost always near the stem, and you get a crack.
The common explanation you’ll hear is that cracking is a calcium problem. It is not. Calcium deficiency causes blossom end rot, a completely different failure where the fruit’s cell walls break down at the blossom end because the plant can’t move enough calcium there fast enough. Cracking is a water and skin-elasticity problem. The two get confused constantly because both are “not enough consistency,” but the fix for one does nothing for the other.
Telling causes apart
Several conditions can trigger the same symptom, so use the pattern and timing to work out which one you’re dealing with:
| Pattern | Likely trigger | What to check |
|---|---|---|
| Concentric rings near stem | Sudden heavy watering or rain after a dry stretch | Recent rainfall and your last watering interval |
| Radial cracks, stem to blossom end | Prolonged uneven watering over several weeks | Whether you’re watering on a fixed schedule or only when soil looks dry |
| Cracking concentrated on one variety only | Thin-skinned variety, often heirloom types | Compare with other varieties in the same bed getting the same water |
| Cracking worse on fruit left ripening longer on the vine | Extended time on the plant after color break | How long you typically leave fruit before picking |
Thin-skinned varieties crack more readily under identical watering conditions because their skin simply has less give. If one variety in your bed is splitting badly and its neighbor isn’t, that’s a strong sign the variety itself is a factor, not just your watering habits.
What to do now
Fruit that has already split is not going to heal, and the crack is now an open door for rot, mold, and insects. Pick cracked fruit right away rather than leaving it on the vine to “see if it’s still good.” If the crack is shallow, dry, and hasn’t attracted anything yet, the fruit is fine to eat once you trim around the split; cook it or eat it soon rather than storing it, since a cracked tomato won’t keep. If you can already see mold, souring, or insect activity inside the crack, discard that fruit.
For fruit that’s still green and unaffected on the same truss, there’s nothing to do to it directly except keep the plant’s water supply steady from here on. If a lot of fruit on one truss is close to ripe and you’re expecting heavy rain, picking slightly early and letting it finish ripening indoors is a reasonable trade against losing it to a split. That’s a similar call to the one you make with fruit that’s stalled on the vine in hot weather, covered in more detail on Tomatoes Not Ripening: What Heat Does, and What to Do About It.
What you can genuinely still influence this season is every truss that hasn’t ripened yet. Cracking is driven by the swing between dry and wet, not by a single bad day, so the plant’s fruit going forward depends entirely on whether you smooth that swing out from here. Don’t spend effort trying to save fruit that’s already split open; put that effort into the watering routine covered in the prevention section below, since that’s what actually protects the rest of the crop.
What does not work
Because cracking gets mistaken for a calcium problem so often, most of the first remedies people reach for target calcium, and none of them address what’s actually happening. Crushed eggshells worked into the soil break down far too slowly to affect calcium availability within a growing season, and in most garden soil calcium was never the limiting factor to begin with. Foliar calcium sprays misunderstand how the plant moves calcium: it travels through the xylem to wherever water is being pulled hardest, which is the leaves, not the fruit, so spraying it onto leaves or even fruit skin does almost nothing to change what’s happening inside the tomato. Adding garden lime to soil that already has adequate calcium doesn’t help either; it raises soil pH, which can cause its own problems if you didn’t need it, and does nothing for a watering-driven crack.
The one-line version worth remembering: in the vast majority of home gardens, the calcium is already present in the soil, and the plant simply cannot move it to the fruit fast enough to matter for cracking, because cracking isn’t a calcium delivery problem in the first place. These remedies aren’t harmful in small amounts, but they cost time and money while the actual cause, inconsistent water, keeps happening untouched.
Mulch is sometimes dismissed as too simple to matter, but that instinct is backwards. The remedies above feel like doing something because they involve buying or applying a product; mulch feels passive because it’s just sitting there. The passive one is the one that actually changes the moisture swing at the root, which is where this problem starts and ends.
Preventing it next time
The single change that matters most is keeping soil moisture consistent, and everything else on this list is secondary to it. A regular watering schedule, deep and even rather than shallow and frequent, prevents the dry-then-flood swing that causes the crack in the first place. Checking soil moisture below the surface rather than judging by how dry the top looks catches the early dry stretch before it turns into a problem after the next rain or watering.
After watering consistency, a few habits matter in roughly this order:
- Mulch around the base of the plant to buffer soil moisture against both dry spells and heavy rain, so the swing the roots experience is smaller either way
- Choose varieties described as crack-resistant if you’ve had repeated problems with a particular thin-skinned variety, since skin elasticity is a real, bred-for trait
- Pick fruit as soon as it’s ripe rather than leaving it on the vine to “hold” for a few extra days, since longer time on the plant after color break gives more opportunity for a moisture swing to hit it
- Avoid a single large watering after letting the soil go very dry; if you’ve missed watering for a stretch, bring the soil back to moist gradually over more than one session rather than soaking it all at once
Even, unstressed soil moisture pays off beyond cracking, too. A plant that isn’t swinging between drought stress and sudden abundance sets fruit more reliably in the first place, which is worth knowing if you’ve also had trouble with flowers dropping or fruit failing to set at all, a separate issue covered on Tomato Plants Not Setting Fruit: Temperature, Pollination and Too Much Nitrogen. If you’re setting up a bed for tomatoes from scratch, working consistent watering into the plan from the start, alongside the basics on How to Grow Tomatoes, saves you from chasing this problem truss by truss all season.
Common questions
Can I still eat a tomato that’s cracked open?
Yes, if you catch it before mold, souring, or insects get into the crack. Trim around the split and use it right away rather than storing it, since a cracked tomato spoils much faster than an intact one.
Will cracked tomatoes still ripen if I leave them on the vine?
They can, but the open crack is exposed the whole time, so the odds of rot or pest damage getting in before it fully ripens go up the longer it stays on the plant. It’s usually safer to pick a cracked fruit as soon as you notice it and let it finish ripening indoors.
Does cracking mean my soil is bad?
Not necessarily. Cracking is usually about the pattern of watering rather than the quality of the soil itself, so a well-amended bed can still produce cracked fruit if watering swings between very dry and very wet.
Are some tomato varieties just going to crack no matter what I do?
Thin-skinned varieties, including many heirlooms, crack more readily than thick-skinned hybrids under the exact same watering conditions, so you may reduce but not fully eliminate it with those varieties. If cracking is a recurring, serious problem in your garden, switching to a variety bred for crack resistance will do more than watering adjustments alone.