Bolting
When leafy or root crops send up a flower stalk too early, which makes leaves bitter and roots woody.
Also known as: Premature flowering, Running to seed
Symptoms and identification
A tall central flower stem shoots up from the middle of the plant. Leaves become bitter, tough or small, roots turn woody or pithy, and the plant stops producing a useful harvest.
Causes
Plants bolt in response to stress, mainly long days, high temperatures, a sudden cold spell after sowing, drought or root disturbance. Cool-season crops such as lettuce, spinach and coriander are most prone.
Organic treatment
Harvest the plant straight away while some leaves are still usable. If you are saving seed, let it flower. Cutting off the flower stalk rarely helps for long.
Prevention
Sow at the right time of year for the crop and choose slow-bolt varieties. Water regularly, mulch to keep roots cool, give shade in hot weather and sow small batches every few weeks.
Chemical treatment (use with care)
No chemical treatment prevents or reverses bolting.