Cilantro

Cilantro (Coriandrum sativum) bolts. That’s the central fact about this herb, and every growing decision flows from it. In warm weather, a cilantro plant can go from leaf to flower stalk in under two weeks, which means a single planting gives you a few weeks of harvest and then you’re done. The solution isn’t to fight the bolting - it’s to plant small amounts every three weeks from early spring through early summer, then again in late summer through fall.

What you’re actually growing

Coriandrum sativum is a single species that produces two distinct products: the fresh leaves (cilantro) and the dried seeds (coriander spice). The same plant gives you both, just at different points in its life cycle. Slow-bolt cultivars like ‘Leisure’ and ‘Santo’ stay in the leaf stage 20 to 30 percent longer than standard types - they don’t stop bolting, but they extend the harvest window enough to matter (Oregon State University Extension, Herbs in the Garden, 2016). If you’re in a region where summers arrive hard and fast, slow-bolt types are worth seeking out.

Leaf cilantro has a flavor profile dominated by aldehydes - the same compounds some people describe as soapy. That perception is genetic, linked to OR6A2 olfactory receptor variation, and no amount of growing technique changes it (Eriksson et al., Flavour, 2012). You either like it or you don’t.

The ROI case

At $1.99 for a packet, cilantro is one of the cheapest herbs to grow from seed. Fresh bunches at retail run $2.00-$4.00 per small bunch, which typically weighs 1.5-3 oz - putting the retail price at $6.00-$8.00/lb based on USDA AMS specialty herb price surveys. Your 0.25 lb yield per planting at $6.00/lb returns $1.50 in grocery value per succession. That’s thin until you account for the fact that a single packet contains 200 to 300 seeds - enough for a dozen or more succession plantings across a season for that same $1.99.

The coriander seed bonus is real. Let two or three plants bolt fully and go to seed. When the seeds turn tan-brown and the umbels dry, cut the whole stem, hang it upside down in a paper bag for a week, and you’ll collect a tablespoon or more of coriander seed per plant. Ground coriander runs $4.00-$6.00/oz at specialty retailers.

Growing requirements

Cilantro germinates best at 55-68°F soil temperature; germination drops sharply above 75°F (Penn State Extension, Herb Production, 2019). This means spring and fall are your windows in most of the country. Crush the seeds slightly before planting - each round seed is actually two seeds fused together, and cracking the hull improves germination rate. Direct sow 1/4 inch deep; cilantro develops a taproot early and transplants poorly once established.

Soil pH of 6.2-6.8 is ideal. Afternoon shade - even just a few hours from a fence or taller crop - delays bolting in warm weather by keeping soil temperatures lower. A north-facing planting in full summer or the shadow of tall tomatoes will extend the leaf harvest.

Water consistently during germination; dry soil combined with heat accelerates bolting. Once plants are 3-4 inches tall, they’re more tolerant of brief dry periods, but consistent moisture keeps them in the leaf stage longer.

What goes wrong

Bolting in heat is the most common frustration. It’s not a pest or disease - it’s a photoperiod and temperature response. Manage it with succession planting and site selection. You can cut the flower stalk as soon as it emerges to delay bolting by a few days, but the plant will redirect energy to producing another stalk within a week.

Damping off (Pythium spp., Rhizoctonia solani) kills seedlings at the soil line, especially in cool, wet conditions. Don’t overwater during germination; good drainage is more important than consistent moisture.

Powdery mildew (Erysiphe heraclei) appears as white powder on leaves in humid conditions with poor air circulation. Space plants 6 inches apart and water at soil level.

Carrot motley dwarf virus (vectored by the carrot-willow aphid, Cavariella aegopodii) causes yellowing and stunting. There’s no treatment. Remove infected plants, control aphid populations with insecticidal soap.

Harvest and storage

Harvest outer leaves and stems once the plant reaches 4-6 inches tall. Cut individual stems rather than pulling - leaving the center intact extends the harvest by several weeks. For maximum flavor, harvest in the morning.

Fresh cilantro doesn’t store long. Wrap loosely in a damp paper towel and refrigerate for up to a week, or store stems upright in a glass of water like cut flowers with a plastic bag loosely over the leaves. For longer storage, blend fresh leaves with water and freeze in ice cube trays - the frozen puree holds flavor reasonably well for cooked applications.

Drying cilantro is not worth the effort; the volatile oils responsible for its flavor dissipate almost completely during drying. Freeze or use fresh.

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Related crops: Basil, Garlic

Related reading: Companion Planting Basics - what the evidence actually says about common pairings