Care problem

Bolting

Lettuce, spinach and herbs shoot up a flower stalk and turn bitter.

What you'll see

• A tall central stalk shoots up and the plant suddenly stretches.
• Flower buds or flowers appear on lettuce, spinach, cilantro or basil.
• Leaves turn bitter, and the plant makes few new leaves.

Why it happens

Heat and long summer days, plus stress such as drought or crowding, switch the plant from making leaves to making flowers and seed.

How to fix it

1. Harvest the leaves promptly; once a flower stalk forms, the leaves only get worse.
2. On basil and cilantro, pinch off flower stems as soon as they show.
3. Or let a few plants flower and set seed to save or self-sow, then sow again in a cooler season.

Keep it from coming back

• Grow lettuce, spinach and cilantro in the cool spring and autumn months.
• Give afternoon shade, keep the soil evenly moist and don't crowd plants.
• Sow small batches every 2 to 3 weeks, and pick slow-bolting varieties.

Read more

• Pinching for bushier plants
• How to protect plants in a heat wave
• Growing vegetables in containers

Sources

• University of Maryland Extension: Flower stalks form or bolting of vegetables
• UC IPM: Bolting
• RHS: Bolting in vegetables

General guidance, not a diagnosis. For valuable, edible or outdoor crops, check with a local extension service or plant expert. Use any product exactly as its label says, and keep children and pets away while it dries.