Why are some of my potatoes hollow inside when I cut them?
Hollow heart in potatoes is caused by rapid, uneven growth — usually after a period of drought followed by heavy watering or rain — and is not a disease.
Hollow heart is a physiological disorder where the interior of the potato develops a cavity, often shaped like a star when cut in cross-section. It's sometimes lined with a corky or brownish tissue. It doesn't look like any disease or pest damage — it's a structural failure of internal tissue growth. The potato is otherwise edible; cut around the hollow.
The mechanism is a growth rate mismatch. During a dry spell, tuber expansion slows. When moisture suddenly becomes abundant — through rain, heavy irrigation, or both — the outer tuber tissues resume growing but the interior tissue can't keep pace. The interior cells die or fail to divide fast enough, leaving a cavity. Large-fruited varieties and large individual tubers are more prone to hollow heart than small or medium-sized potatoes.
Consistent soil moisture is the main prevention. Mulching potato beds heavily reduces soil moisture swings significantly. Even, regular watering — rather than dry periods followed by deep soaking — keeps tubers expanding at a consistent rate. Planting seed pieces at the right spacing also helps; overcrowded plantings tend to produce a few very large tubers (more prone to hollow heart) while properly spaced plants produce more medium-sized ones.
Some varieties are more prone to hollow heart than others. Russet-type potatoes are generally more susceptible than red or yellow-fleshed varieties. If it's been a consistent problem in your garden, trying a different variety the following season may be more effective than any cultural adjustment.
- AphidSoft, clustered insects on new growth causing curled leaves and sticky honeydew.
- Bacterial WiltCucurbit vines wilt rapidly despite moisture; cut stem shows sticky ooze that threads when pulled apart.
- Black RotV-shaped yellow lesions at brassica leaf margins with blackened veins inside — a bacterial disease that moves through the vascular system.
- Brown Marmorated Stink BugSunken, corky dimples on fruit and pods caused by a mottled brown shield bug feeding through the skin.
- Carrot Rust FlyRusty tunnels through carrot and parsnip roots made by small white maggots feeding inside the root.
- What is that black leathery patch on the bottom of my tomatoes?Blossom end rot is a calcium deficiency at the fruit level, almost always caused by irregular watering rather than a lack of calcium in the soil.
- Why are my tomatoes cracking and splitting?Tomato skin cracks when the fruit expands rapidly after a period of drought — inconsistent watering is almost always the cause, though some varieties are simply crack-prone.
- We're in a drought — how do I keep my garden going?Mulch, deep infrequent watering, and cutting back on what you're growing are the three adjustments that make the biggest difference during drought conditions.