Why Are the Inner Leaves of My Cabbage Brown and Burnt?

Cutting open a cabbage head and finding the inner leaves brown, papery, and scorched-looking — while the outer leaves appear healthy and green — is the hallmark of internal tipburn. This is a physiological disorder, not a disease, caused by localised calcium deficiency in the innermost leaves during rapid head formation. It is distinct from black rot (a bacterial disease) because there is no smell, no black vein discolouration, and no spreading lesion — just the characteristic brown leaf edge and tip burn on inner leaves only.

What causes tipburn

Calcium is an immobile nutrient in plants — it moves only in the transpiration stream through the xylem and cannot be redistributed once deposited. The innermost leaves of a forming cabbage head have very low transpiration (they are enclosed by the outer leaves and have minimal air movement across their surfaces), so they receive minimal calcium even when calcium is abundant in the soil. During periods of rapid growth — particularly in warm weather — the innermost leaves grow very quickly without receiving adequate calcium, and the cell walls in the leaf margins fail, producing the characteristic browning.

Water stress as the trigger

Tipburn is most severe after periods of dry weather followed by rapid growth with good moisture — the boom-bust cycle that drives very fast cell expansion. Erratic watering triggers the worst tipburn. Consistent, steady soil moisture maintains steady growth and steady calcium movement, significantly reducing the severity of the disorder. Mulching to retain soil moisture and watering regularly during dry periods prevents most tipburn in practical garden growing.

Is tipburn-affected cabbage safe to eat?

Yes — tipburn is a cosmetic and quality issue, not a food safety one. Remove and discard the browned inner leaves and the remaining head is perfectly edible. Mild tipburn barely affects usability. Severe tipburn can make the inner portion of the head unappetising and may allow secondary bacterial rots to establish in the damaged tissue — in this case, harvest promptly and use quickly rather than storing.