Troubleshooting
Loose-leaf Lettuce problems — and how to fix them
Loose-leaf Lettuce (Lactuca sativa var. crispa) is generally forgiving once you match its basics, but a few issues come up again and again. Here is what each one looks like, why it happens, and the fix.
Bolting
Long days and temperatures above 24°C (75°F) trigger premature flowering, turning leaves bitter. Sow in early spring or late summer and choose slow-bolt varieties.
Downy mildew
Grey-white coating on leaf undersides in humid, cool conditions. Improve airflow, avoid overhead watering, and remove affected leaves promptly.
Tip burn
Brown leaf margins caused by calcium deficiency or rapid temperature swings rather than lack of soil calcium. Ensure even watering and avoid large fluctuations in day/night temperatures.
Prevent loose-leaf lettuce problems before they start
Most loose-leaf lettuce issues are care-mismatch, not bad luck. Dial in the basics:
- Common lettuce problems — the species this cultivar belongs to
- What's wrong with my plant? — the diagnosis apps compared
- Loose-leaf Lettuce watering schedule
- Loose-leaf Lettuce light requirements
- Best soil mix for loose-leaf lettuce
- Loose-leaf Lettuce temperature & humidity
- Full loose-leaf lettuce care guide
Looking for loose-leaf lettuce in general rather than its problems? Read the full loose-leaf lettuce care guide — light, water, soil and feeding.
Loose-leaf Lettuce problems — FAQ
Why is my loose-leaf lettuce bolting?
Long days and temperatures above 24°C (75°F) trigger premature flowering, turning leaves bitter. Sow in early spring or late summer and choose slow-bolt varieties.
Why is my loose-leaf lettuce downy mildew?
Grey-white coating on leaf undersides in humid, cool conditions. Improve airflow, avoid overhead watering, and remove affected leaves promptly.
Why is my loose-leaf lettuce tip burn?
Brown leaf margins caused by calcium deficiency or rapid temperature swings rather than lack of soil calcium. Ensure even watering and avoid large fluctuations in day/night temperatures.