Why does my coriander always bolt?

Coriander bolts fast in heat — anything above 25°C and long summer days triggers it within weeks. UK summer is the worst time for leaf coriander. Sow early (March–April) and late (August–September) instead of June–July. Choose slow-bolting cultivars (Calypso, Confetti) for any summer sowings. Once a plant bolts you can't stop it; pull it and re-sow.

When should I sow coriander seed in the UK?

Late March under cloches in southern England; April outdoors. Successional sowings every 3 weeks until early June, then skip July (too hot), and resume in August for an autumn crop. Hardy varieties can be sown into September for winter cropping under cloches. Coriander wants soil above 10°C to germinate.

Is coriander an annual or biennial?

Annual — grows from seed, flowers, sets seed, dies, all in one season. Most plants bolt and die in 8–12 weeks. The seed they set is the spice (called coriander seed in the UK; Americans call the seed coriander but the leaf cilantro). Save your own seed by letting a few plants bolt and harvesting when the heads turn brown.

What's the difference between coriander and cilantro?

Same plant. Coriander is the UK name and refers to both leaf and seed. Cilantro is the American name for the leaf only (they call the seed coriander). Some recipes specify coriander leaf to disambiguate. UK-grown plants are always called coriander.

Can I grow coriander in containers in the UK?

Yes — and it's often easier than outdoors because you can move pots into shade in hot weather to delay bolting. A 30 cm pot grows enough for a household. Successional sowings every 3 weeks keep the supply going. Indoor windowsill sowings work year-round but the leaves are weaker-flavoured than outdoor.

When is coriander ready to harvest?

Leaf: from about 4 weeks after sowing, when stems are 15 cm long. Pick whole stems from the base. Seed: 12–16 weeks after sowing, when the seed heads have turned brown and the seeds rattle when shaken. Cut whole plants, hang under cover to dry for a fortnight, then thresh.

Coriandre (plante entière)

Coriandrum sativum

Sow coriander seed direct from late March to August in successional batches every three weeks. It bolts fast in heat — UK summer is exactly the wrong time for leaf coriander, so sow in spring and again in autumn for cool-season cropping. The leaf (cilantro to Americans) is what most home gardeners want; the seed is the spice and gathers naturally once the plant bolts. Coriander is hardy (RHS H4) and tolerates light frost as young plants. Choose slow-bolting cultivars (Calypso, Confetti) for any summer sowings. Sow thinly into well-drained soil; pick leaves from the bottom of the plant before flower stems appear. One plant gives leaf for about three weeks, so plant successionally.

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