How to grow coriander
Overview
Coriander (Coriandrum sativum) is a fast-growing annual herb grown for its fresh leaves (cilantro) and dried seeds. Both parts are used widely in Asian, Latin, and Middle Eastern cooking. It bolts quickly to seed in hot weather, so success depends on timing and steady moisture.
Varieties
- Slow Bolt — A slower-bolting variety that gives a longer leaf harvest before going to seed, ideal for temperate and subtropical gardens.
- Santo — A popular commercial variety with good leaf yield and strong flavour, widely available in Australian seed packets.
- Confetti — A fine-leafed variety with a milder flavour, often used in salads and garnishes.
Soil Preparation
Coriander prefers well-drained, fertile soil with a pH between 6.0 and 7.0. Before planting, dig in 2–3 cm of well-rotted compost or aged manure. Avoid heavy clay soils; if your soil is dense, grow in raised beds or large pots with quality potting mix.
Growing Guide
Sow coriander seed directly into garden beds or deep pots, as it dislikes transplanting. Space seeds 2–3 cm apart in rows 20 cm apart, and cover lightly with 5 mm of fine soil. Keep the soil consistently moist but not waterlogged. For a continuous supply, sow a new batch every 3–4 weeks. In hot weather, provide afternoon shade or grow in a cooler spot to delay bolting. Thin seedlings to 15 cm apart once they are 5 cm tall.
Sowing
Sow coriander seed 5 mm deep, 2–3 cm apart, directly into the garden or deep pots. Germination takes 7–14 days in warm soil (15–25°C). Do not transplant — coriander develops a taproot and resents disturbance. For best results, sow in situ every 3–4 weeks.
Care
Feed coriander every 4–6 weeks with a balanced liquid fertiliser (e.g., seaweed or fish emulsion) to promote leafy growth. Remove flower heads promptly if you want to extend leaf harvest. Keep the soil surface mulched to retain moisture and suppress weeds.
Companion Planting
Coriander grows well with leafy greens like lettuce, spinach, and silverbeet, and with dill and chervil. Avoid planting near fennel, which can cross-pollinate and reduce seed quality. It also benefits from being near tomatoes, which help repel aphids.
Common Pests & Risks
Aphids are the main pest on coriander, especially on young growth. Spray with a strong jet of water or use a dilute soap solution. Fungal diseases like powdery mildew can appear in humid conditions; improve air circulation by spacing plants well and avoid overhead watering.
Harvesting
Harvest coriander leaves when plants are 10–15 cm tall, before flower stems appear. Cut outer leaves first, leaving the centre to keep growing. For seeds, let some plants flower and set seed; cut the seed heads when they turn brown and dry them in a paper bag. Seeds are ready when they easily fall off the stem.
In the Kitchen
Use fresh coriander leaves as a garnish or stirred into curries, salsas, and salads just before serving. The leaves lose flavour quickly when cooked, so add them at the end. Dried seeds are ground as a spice for curries, pickles, and baked goods. Store fresh leaves in a damp paper towel in the fridge for up to a week.
Troubleshooting
Yellow leaves: caused by overwatering or poor drainage. Let soil dry slightly between waterings. Brown leaf edges: often from heat stress or wind. Provide afternoon shade or a windbreak. Plants bolting early: triggered by hot weather or long days. Sow in cooler months or choose slow-bolt varieties. Stunted growth: usually from overcrowding. Thin seedlings to 15 cm apart. Powdery mildew: white coating on leaves from high humidity. Improve air flow and avoid overhead watering.