Growing coriander

Quick answer

Direct sow coriander into its final position in spring, then sow a small batch every few weeks rather than one large crop. This repeated sowing is called succession sowing. Give it bright light, freely draining soil and steady moisture. In hot, dry conditions, light afternoon shade and prompt watering can delay flowering, but every leaf crop will eventually bolt.

For repeated picking, harvest a few outer stems once plants are 10–15cm tall, leaving the centre growing. Alternatively, cut young plants as a whole short-term crop and use succession sowing for later harvests. Leave selected plants to flower if you want edible blooms, pollinator value or coriander seed. Choose a slow-bolting cultivar when leaves are the priority.

Leaves, flowers or seeds

Coriander and cilantro are names for the same plant, Coriandrum sativum. In UK usage, coriander commonly describes both its fresh leaves and dried seed; cilantro usually means the fresh leaf. The plant changes form as it matures: rounded lower leaves give way to finer upper foliage, then white flower umbels (umbrella-shaped clusters of flowers) and round fruits.

Decide on the intended harvest before sowing. Leaf cultivars selected for slower bolting extend picking, while a seed crop needs an early enough sowing for fruits to ripen. Microgreens are a separate, very short crop and can be sown densely because they are harvested as seedlings.

The RHS coriander guide recommends small repeated sowings for leaves and notes that the plant dislikes transplanting.

Light, soil and temperature

Provide four to six hours of direct light or more in mild weather. Spring and autumn crops can use full sun; in a hot site, afternoon shade may reduce heat and water stress. Deep shade makes weak growth and should not be used as a general cure for bolting.

Use weed-free, crumbly soil or fresh peat-free potting compost that drains while retaining some moisture. Avoid very rich feeding, which can produce soft growth without preventing flowering. Coriander has a taproot, so loosen compacted ground and choose pots deep enough for stable moisture and root development.

Established plants tolerate cool conditions, but this does not establish a reliable minimum temperature or guarantee frost tolerance. Sowing conditions are a separate consideration: cold saturated soil slows germination. Wait until a seedbed is workable, or make the earliest sowings under simple protection.

Direct and succession sowing

Sow seed in shallow rows or small stations, cover lightly with soil or compost and water gently. Keep the top layer moist through germination. The RHS coriander guide gives an outdoor emergence time of one to three weeks, depending on temperature; cold saturated soil can slow germination. The dry round “seed” is a fruit containing seeds; it does not need aggressive crushing. Use the 10–20cm spacing range according to the intended harvest: closer spacing suits short-term leaf crops, while plants kept for seed need thinning to 20cm apart to mature. Thin crowded seedlings so air and light reach each plant, using sound thinnings in the kitchen.

Direct sowing avoids root disturbance and usually produces stockier plants. If starting in modules (seed trays divided into individual growing cells), sow a small cluster in each cell and transplant the intact plug promptly before roots circle. Do not tease individual seedlings apart.

For a continuous leafy crop, repeat a modest sowing every two to four weeks through suitable weather. The RHS herb-growing advice specifically recommends succession sowing fast-bolting herbs such as coriander.

Containers and indoor crops

Use a pot at least 20cm wide with unobstructed drainage. A deeper trough is more forgiving than a shallow windowsill tray. Choose how many plants to retain according to the intended harvest and available spacing, rather than pot volume alone. Sow several plants, then thin enough to keep the remaining foliage open, allowing 20cm between plants kept for seed; do not expect a crowded supermarket pot to develop into a long-lived specimen.

Indoors, place coriander at the brightest suitable window or beneath a planned grow light. A generally bright room is often too dim. Warm, dry indoor air can accelerate flowering, while repeated waterlogging causes root loss. Turn the pot and provide gentle airflow so stems remain upright.

Microgreens can be grown in a shallow tray for a one-time cut. Use clean seed sold for sprouting or edible cropping and follow safe microgreen hygiene.

Water, feed and manage bolting

Water the root zone when the surface begins to dry, soaking the medium evenly and allowing excess to drain. Alternating drought and saturation stresses the plant. A light mulch around established outdoor rows can buffer moisture without touching young stems.

Garden plants in reasonable soil rarely need extra feed. Container crops can receive a dilute balanced feed only if growth and product instructions justify it. High feed rates do not stop bolting.

Bolting is the natural transition to flowering, intensified by heat, drought, root restriction and increasing day length. Remove early flower stems if leaves are the only goal, but replace the crop through succession sowing rather than repeatedly cutting a plant that is committed to seed.

Diagnosing coriander problems

Symptom	Likely causes to investigate	First checks
Uneven germination	Dry seedbed, cold wet soil or old seed	Check moisture at sowing depth and the seed date. If dry, restore steady moisture; if saturated, restore drainage rather than adding more water.
Long pale stems	Insufficient light or crowding	Check light level and spacing. Improve light if insufficient, or thin crowded seedlings so light and air reach the remaining plants.
Plant flowers while small	Heat, drought, root restriction or season	Check pot depth, recent weather and moisture. Maintain steady moisture and replace bolting leaf crops through succession sowing.
Yellow lower leaves	Saturated roots, low light or crowding	Check drainage and root-zone smell. Restore obstructed drainage if the roots are saturated; also check for insufficient light or crowding and improve light or thin plants as needed.
Distorted sticky tips	Aphids	New leaves and nearby ant activity
White or grey leaf coating	Possible mildew; persistent leaf wetness is a condition to investigate, not an identification of the coating	Check airflow, persistent leaf wetness and whether the coating spreads. Provide gentle airflow and water the root zone.

Use physical barriers and hygiene before reaching for treatments. Any product used on a herb must be labelled for edible crops, with its harvest interval followed.

Harvest leaves and seed

Begin leaf harvest when plants are about 10–15cm tall. For repeated picking from the same plants, take a few outer stems from each and leave the centre growing. Alternatively, harvest a whole short-term crop by cutting just above soil level. For this second approach, plan later harvests from successive sowings rather than relying on continued picking from the cut plants. Cool harvested leaves quickly and use them within a few days.

Flowers are edible and useful to insects. For seed, allow selected heads to turn from green to tan, then cut them before ripe fruits scatter. Dry the heads in a ventilated paper bag, rub out the fruits and store them dry and labelled. Green coriander seed can also be used fresh for a different flavour.

Record which sowing dates gave the longest leafy window. Local temperature and day length will reveal a more useful schedule than assuming one spring sowing can supply the whole season.

Sources and review basis

1. How to grow coriander — Royal Horticultural Society
2. Growing and harvesting herbs — Royal Horticultural Society

Sowing intervals are working ranges. Adjust them to crop speed, temperature and the amount your household actually uses.