Cilantro/Coriander: Indoor or Direct Sow or Potted Plant Herb
How to Sow and Plant
Cilantro may be grown from seed sown early indoors and transplanted outside after frost or in a container, or sown directly in the garden after danger of frost, or planted as a potted plant. The seeds are called coriander and the leafy green part in the cilantro.
Sowing Seed Indoors:
- Sow cilantro seeds indoors 6-8 weeks before the average last frost date in spring using a seed starting kit.
- Sow seeds ¼ inch deep in seed starting formula
- Keep the soil moist at 70 degrees F
- Seedlings will emerge in 14-21 days
- As soon as the seedlings emerge, provide plenty of light on a sunny windowsill, or grow seedlings 3-4 inches beneath fluorescent plant lights turned on 16 hours per day, off for 8 hours at night. Raise the lights as the plants grow taller. Incandescent bulbs will not work for this process because they will get too hot. Most plants require a dark period to grow, do not leave lights on for 24 hours.
- Seedlings do not need much fertilizer, feed when they are 3-4 weeks old using a starter solution (half strength of a complete indoor houseplant food) according to manufacturer’s directions.
- If you are growing in small cells, you may need to transplant the seedlings to 3 or 4 inch pots when seedlings have at least 2 pairs of true leaves before transplanting to the garden so they have enough room to develop strong roots
- Before planting in the garden, seedling plants need to be “hardened off”. Accustom young plants to outdoor conditions by moving them to a sheltered place outside for a week. Be sure to protect them from wind and hot sun at first. If frost threatens at night, cover or bring containers indoors, then take them out again in the morning. This hardening off process toughens the plant’s cell structure and reduces transplant shock and scalding.
Sowing Directly in the Garden:
- Direct sow in average soil in full sun after all danger of frost.
- Remove weeds and work organic matter into the top 6-8 inches of soil; then level and smooth.
- Sow seeds evenly and cover with ¼ inches of fine soil.
- Firm the soil lightly and keep evenly moist.
- Seedlings will emerge in 14-21 days.
- Thin to 12 inches apart when seedlings have three pairs of leaves.
Planting in the Garden:
- Select a location in full sun where water drains quickly after a rainfall.
- Prepare the bed by turning the soil under to a depth of 8 inches. Level with a rake to remove clumps of grass and stones.
- Dig a hole for each plant large enough to amply accommodate the root ball.
- Carefully remove the plant from its pot and gently loosen the root ball, if tight, with your hands to encourage good root development.
- Place the top of the root ball even with the level of the surrounding soil. Fill with soil to the top of the root ball. Press soil down firmly with your hand leaving a slight depression around the plant to hold water.
- Use the plant tag as a location marker.
- Water thoroughly, so that a puddle forms in the saucer you have created. This settles the plants in, drives out air pockets and results in good root-to-soil contact.
- Do not allow plants to dry out, but never let the soil stay wet.
How to Grow
- Sow every 3 weeks during the growing season to ensure steady supply.
- Do not fertilize.
- Keep weeds under control during the growing season. Weeds compete with plants for water, space and nutrients, so control them by either cultivating often or use a mulch to prevent their seeds from germinating.
- Mulches also help retain soil moisture and maintain even soil temperatures. For herbs, an organic mulch of aged bark or shredded leaves lends a natural look to the bed and will improve the soil as it breaks down in time. Always keep mulches off a plant's stems to prevent possible rot.
- Keep plants well-watered during the growing season, especially during dry spells. Plants need about 1 inch of rain per week during the growing season. It's best to water with a drip or trickle system that delivers water at low pressure at the soil level. If you water with overhead sprinklers, water early in the day so the foliage has time to dry off before evening, to minimize disease problems. Keep the soil moist but not saturated.
- Monitor for pests and diseases. Check with your local Cooperative Extension Service for pest controls recommended for your area.
Harvesting and Preserving Tips
- Harvest cilantro leaves before the flower stem has developed.
- Harvest coriander seeds once they start turning from green to gray-brown.
- The leaves may be dried or frozen. Use them fresh in Asian and Mexican dishes; they taste is better than the smell.
- The ripe seeds are an important ingredient in curry. They are also used as a pickling spice or sugar-coated and eaten as candy.
Common Disease Problems
Bacterial Leaf Spot: First signs are small translucent spots with a broad yellowish edge that slowly enlarge and become angular or irregularly circular with a reddish center. It thrives in cooler temperatures. The disease may also affect and disfigure flower heads. Burpee Recommends: Remove infected plants. Rotate crops with plants in a different family. Avoid overhead watering. Do not work around plants when they are wet.
Botrytis Blight: Causes the older leaves and the center of the plant to rot. It can start with a yellowish brown irregular spots on the leaves or water soaked spots on the stems. The fungus turns a fuzzy gray and emits a cloud of spores when touched. Burpee Recommends: Remove infected plants and plant debris to avoid the spread of the disease and make sure plants have good air circulation. Keep organic mulches away from the plants as spores can live in the organic matter. Use pea gravel as mulches they will help decrease humidity around the plants.
Damping Off: This is one of the most common problems when starting plants from seed. The seedling emerges and appears healthy; then it suddenly wilts and dies for no obvious reason. Damping off is caused by a fungus that is active when there is abundant moisture and soils and air temperatures are above 68 degrees F. Typically, this indicates that the soil is too wet or contains high amounts of nitrogen fertilizer. Burpee Recommends: Keep seedlings moist but do not overwater; avoid over-fertilizing your seedlings; thin out seedlings to avoid overcrowding; make sure the plants are getting good air circulation; if you plant in containers, thoroughly wash them in soapy water and rinse in a ten per cent bleach solution after use.
Powdery Mildew: This is a fungus disease that causes a white powdery look on the foliage. This disease weakens plants as it inhibits their ability to make carbohydrates for themselves using sunlight. Burpee Recommends: You can remove infected plant areas, increase air circulation, and try to reduce the humidity in the room. Check with your Cooperative Extension Service for fungicide recommendations.
Root Knot Nematodes: Microscopic worm-like pests that cause swellings (galls) to form on roots. Plants may wilt or appear stunted. This is a serious problem in many Southern states. Burpee Recommends: Do not plant into infested soil. Grow resistant varieties. Try planting ‘Nema-Gone’ marigolds around your plants.
Common Pest and Cultural Problems
Aphids: Greenish, red, black or peach colored sucking insects can spread disease as they feed on the undersides of leaves. They leave a sticky residue on foliage that attracts ants. Burpee Recommends: Introduce or attract natural predators into your garden such as lady beetles and wasps who feed on aphids. You can also wash them off with a strong spray, or use an insecticidal soap.
Cutworms: These insects cut off the seedlings at the soil level. Burpee Recommends: Place a paper cup collar (use a coffee cut with the bottom cut out) around the base of the plant. They are usually mostly a problem with young seedlings. You can also control by handpicking and controlling weeds, where they lay their eggs.
Deer: Plants may be eaten to the ground. Burpee Recommends: Try a deer repellent or physical barrier for young plants.
Slugs: These pests leave large holes in the foliage or eat leaves entirely. They leave a slime trail, feed at night and are mostly a problem in damp weather. Burpee Recommends: Hand pick, at night if possible. You can try attracting the slugs to traps either using cornmeal or beer. For a beer trap, dig a hole in the ground and place a large cup or bowl into the hole; use something that has steep sides so that the slugs can’t crawl back out when they’re finished. Fill the bowl about ¾ of the way full with beer, and let it sit overnight. In the morning, the bowl should be full of drowned slugs that can be dumped out for the birds to eat. For a cornmeal trap, put a tablespoon or two of cornmeal in a jar and put it on its side near the plants. Slugs are attracted to the scent but they cannot digest it and it will kill them. You can also try placing a barrier around your plants of diatomaceous earth or even coffee grounds. They cannot crawl over these.
Whitefly: These are small white flying insects that often rise up in a cloud when plants are disturbed or brushed against. Burpee Recommends: They are difficult to control without chemicals. Try hot pepper wax or insecticidal soap. Check with your Cooperative Extension Service for pesticide recommendations.
What is the difference between cilantro and coriander? They are the exact same plant. Cilantro is the leafy plant part and coriander is the seed produced.
Can I grow coriander in containers? Yes, coriander works well in containers.
How can I keep my cilantro from bolting? The plants may bolt in hot weather, if it is too dry or if plants are overcrowded. If this happens stop harvesting the leaves and allow the seeds to develop for coriander.
Can I use coriander as a companion plant? Yes, coriander attracts beneficial insects to your garden, and improves the growth of spinach and tomatoes and asparagus.
Can I grow coriander indoors? Yes you can grow it in doors as long as you have plenty of sun, or grow under lights.