Coriander Bolting — How to Keep It in Leaf Longer

Coriander is notorious for bolting — sending up a flower stalk and abandoning leaf production — often just a few weeks after sowing. It is one of the most bolt-prone herbs in the garden, and many growers give up in frustration after watching successive plants go to seed before they have harvested more than a handful of leaves. But with the right approach, you can extend the leaf-producing period significantly.

Why Coriander Bolts So Readily

Coriander is a cool-season herb that evolved in a climate with mild winters and hot, dry summers. It is programmed to flower quickly when it senses heat, long days, or stress. Any combination of warm temperatures, root disturbance, drought, or crowding can trigger bolting within days. In the UK and similar climates, the period from late May through August is particularly problematic — the long days and warming temperatures push coriander to flower faster than you can harvest it.

Sow at the Right Time

The two best windows for leaf coriander are early spring (March to April) and late summer (August to September), when temperatures are cooler and day length is decreasing. Plants sown in these windows have significantly slower bolt rates and produce leaves for six to eight weeks rather than two to three. Avoid sowing in May or June if leaf production is your goal — these plants will flower almost immediately in midsummer.

Always Sow Direct — Never Transplant

Coriander has a delicate taproot that resents disturbance. Transplanting even small seedlings almost always triggers immediate bolting. Sow seed directly into its final position — either in the ground or in a deep container — and thin to 5–8 cm spacing rather than moving plants around. If you buy supermarket coriander, it has likely already been stressed in transit and will bolt very quickly; treat it as a short-term harvest rather than a plant to nurture.

Provide Afternoon Shade in Hot Weather

Shading coriander during the hottest part of the day (noon to 3pm) noticeably slows bolting in summer. Plant it on the east-facing side of taller plants, use shade cloth, or grow it in a spot that gets morning sun and afternoon shade. Keep the soil consistently moist — drought stress is a rapid bolt trigger. Mulching around plants helps retain moisture and keeps root temperatures lower.

Succession Sow Every Three Weeks

The most practical solution is to accept that coriander bolts and plan around it with succession sowing. Sow a small batch every two to three weeks from early spring, and you will always have plants in the leaf-producing stage. Let some plants go to seed — the coriander seeds are a useful spice in their own right, and self-sown seedlings will appear the following spring. Varieties labelled "slow bolt" such as Confetti or Leisure genuinely do outperform standard varieties by one to two weeks in warm weather.