Why Are My Plums Cracking at the Skin?

Fruit cracking — where the skin of a plum splits open as it approaches ripeness — is a familiar late-summer frustration for plum growers. Cracked plums are not only visually unappealing but they become entry points for brown rot and other pathogens, dramatically shortening shelf life. The primary cause is well understood, and with the right management approach it can be largely prevented.

Irregular water supply — the main cause

When a plum tree experiences drought stress followed by a sudden heavy rainfall or irrigation, the fruits take up water rapidly and the flesh expands faster than the skin can stretch. The skin splits. This pattern is most common in late summer as fruits approach maturity: a dry July and August followed by heavy August rain often produces widespread cracking. The solution is to maintain consistent soil moisture throughout the fruit development period rather than allowing the soil to dry completely between waterings. Mulching with a thick layer of organic material around the root zone is the most practical way to even out soil moisture for non-irrigated trees.

Overhead irrigation wetting the fruit directly

Watering with a sprinkler that wets the fruit surface directly causes localised moisture uptake through the skin, which can trigger cracking independently of root uptake. Water at the base of the tree, directing moisture to the root zone, not into the canopy. Drip irrigation or soaker hose around the drip line is ideal.

Thin-skinned varieties

Some plum varieties have naturally thin, delicate skin that cracks readily in wet seasons. Victoria, the most widely grown garden plum, is notably prone to cracking when rainfall occurs near harvest time. If cracking is a recurring problem in your variety and garden, consider that the variety itself may be part of the issue. Varieties such as 'Blue Tit', 'Opal' or 'Czar' tend to be less susceptible.

Picking before cracking occurs

If wet weather is forecast when your plums are approaching ripeness, harvest them a day or two early — slightly underripe plums ripen well on a cool windowsill and will not crack once picked. Cracking only happens on the tree when the fruit is still under the influence of the tree's water uptake system.

Dealing with already-cracked fruit

Pick cracked plums immediately — once the skin splits, brown rot can enter within hours in warm weather. Use cracked plums the same day for jam, chutney or freezing rather than fresh eating or storage.