Cilantro

Quick facts

Why cilantro bolts so fast

Clemson defines bolting as "prematurely growing a flower stalk." Every source names heat. Texas A&M says cilantro starts to bolt when temperatures exceed 85°F, OSU's Food Hero program puts the line at 80°F, and UMD says hot, humid weather makes plants flower and set seed. Oregon State vegetable breeder Jim Myers adds that "both temperature and day length influence flowering," and UF/IFAS Gardening Solutions says the plant goes to seed "when the days get long and warm." OSU says cilantro sown in late June or early July bolts during long, hot summer days, while spring and fall plantings give leaves for weeks or months first.

Ways to delay bolting

• Sow in early spring and again in late summer (OSU), in a cooler part of the garden (OSU) or with afternoon shade (UMD).
• Mulch to keep the soil cool, water well and grow plants close together (USU).
• Pinch off flower stems to extend the leaf harvest (UMD).
• Choose a slow-bolting variety (table below), although Wisconsin cautions that none hold up well under high temperatures and long days.

When to sow

Illinois sows directly after the last frost because the taproot makes transplanting difficult, and OSU agrees; USU allows indoor starts 4–6 weeks ahead with minimal root disturbance, and Clemson sets transplants out after the last frost. Look up your dates with frost dates explained and count forward with the planting calendar.

Denver Urban Gardens' youth-garden list also calls it a quick spring or fall herb.

Succession sowing, step by step

1. Sow small batches. UF/IFAS Gardening Solutions sows a few seeds every few weeks; OSU sows 10–15 seeds per foot of row.
2. Choose an interval. Every 2–3 weeks (UMD, Wisconsin), every 3–4 weeks (Illinois, OSU Food Hero) or weekly (Texas A&M).
3. Sow shallow. ¼–½ in deep (Texas A&M, Wisconsin, UF/IFAS Hardee County), ¼ in (Clemson) or ½ in (OSU).
4. Keep seedbeds moist; water needs peak during germination and establishment (Texas A&M). UF/IFAS Hardee County soaks seed overnight and refrigerates it if nights are above 60°F.
5. Pause in the hottest weeks. Wisconsin does not recommend summer plantings because plants generally bolt before producing much, and OSU advises avoiding peak summer heat. Start again as the weather cools.

Spacing and containers

For grid beds, compare square foot gardening spacing.

• Pot size. UMD puts cilantro with basil, thyme, mint and marjoram in its smallest class: at least 1–3 gal of growing media, 4–6 in deep. Clemson says single plants suit medium-sized containers. More crops: container sizes for vegetables.
• Shallow roots. OSU Food Hero says shallow containers work, with regular watering so the soil does not dry out.
• A pot variety. Illinois lists 'Pot Cilantro 99057', developed for pot culture and sown directly into containers.

Harvesting leaves

1. Start at about 6 in tall (Illinois, Wisconsin, OSU Food Hero, UF/IFAS); UMD picks a few leaves once they reach 4–6 in.
2. Cut outer leaves once they are 4–6 in long, or cut the whole plant 1–2 in above the soil (Texas A&M, UF/IFAS Hardee County); check daily, since it goes to seed quickly (OSU Food Hero). Hardee County says one plant yields two cuttings before it matures.
3. Store dry leaves loosely wrapped in the refrigerator for about a week (Illinois), or freeze or dry them (USU).

Saving coriander seed

Texas A&M likens the seed's flavor to orange; it goes into pickling spice and curry powder. UMD says seed is usable only when fully mature, in mid-summer; USU expects it in late summer or early fall.

1. Let some plants flower, spaced wider than leaf plants (table above).
2. Wait for brown heads (UMD, Illinois, USU). Wisconsin harvests when seeds turn light brown and the whole plant has dried.
3. Cut and dry. Cut the heads or whole plants and dry them in a paper bag in a cool, dry place (Illinois, OSU Food Hero).
4. Shake and store. Shake the bag, roll the pods between your hands to free the seed and keep it in closed containers (Illinois); OSU Food Hero says it lasts 3–4 years.

Plants left to mature drop seed and come up again (UMD, Illinois). OSU notes the blossoms attract beneficial insects; see the companion planting chart.

Slow-bolting varieties

Pests and diseases

This page gives no pesticide or fertilizer rates. Texas A&M, UF/IFAS and USU name control products in their own publications; ask your county extension office to confirm a diagnosis before treating.

Where sources disagree

Small-space checklist

• Sow in early spring and again as late summer cools; skip the hottest weeks.
• Re-sow a small batch every 2–4 weeks for a steady supply.
• Use a pot of at least 1–3 gal, 4–6 in deep, in sun with some afternoon shade as it warms.
• Start cutting at about 6 in and pinch off flower stems.
• Leave a few plants to brown for coriander seed.

More crop pages: parsley, basil, lettuce and spinach.