Overview
- Name: Coriander (Cilantro in North America)
- Botanical Name: Coriandrum sativum
- Plant Family: Apiaceae (Carrot Family)
- Native to: Mediterranean and Near East/Western Asia
Description
Coriander is an annual herb, so it only lives for a single growing season, and grows up to 60 cm (24 in) tall, featuring delicate, lace-like leaves. The lower leaves are broad and lobed, while the upper leaves are finely divided and slender. It produces small, white to very pale pink flowers arranged in clusters (umbels). Once pollinated, these flowers produce yellow-brown oval-shaped fruit which contains two round, aromatic seeds that can also be used as a spice.
Interesting Facts
- Both the leaves and seeds are used in cooking, though they have different flavours.
- Coriander has been cultivated for over 3,000 years, making it one of the oldest known herbs.
- Ancient Egyptians used coriander in perfumes and for medicinal purposes.
- Some people perceive coriander leaves as tasting soapy due to a genetic trait involving the OR6A2 gene, which is responsible for detecting aldehyde compounds.
- The essential oils from coriander seeds are used in cosmetics and flavourings.
Basic Growing Information
- Sun Requirements: Full sun to partial shade
- Water Requirements: Medium
- Soil Types and Properties: Fertile, well-draining soil with organic matter
- Soil pH: 6.2 – 6.8
- Pot Size for Container Growing: At least 25 cm (10 inches) deep
Planting
Coriander is a cool-season crop that grows optimally in areas with damp, cool springtime weather with summer temperatures between 16-21°C (60-70°F). The plant can tolerate light frost, but exposure to high temperatures will cause the plants to bolt, to prematurely go to seed.
It grows best in well-draining soil and can be grown in a variety of soils such as sandy loam, loam and clay soils as long as there is sufficient drainage.
- Best Time to Plant:
- Climates with freezing winters: Sow seeds indoors 3-4 weeks before the last frost; transplant outdoors in early spring.
- Climates with milder winters: Sow seeds directly outdoors in spring or autumn.
Note: Check gardening calendars for the best planting times in your location
- Spacing: 15 cm (6 in) between plants, 30 cm (12 in) between rows
- Seed Sowing Method: Sow seeds directly into the ground.
- Seed Sowing Depth: 1 cm (0.5 in) deep
- Time to Harvest: 4-6 weeks when planted from seed to harvest leaves, 8-12 weeks when planted from seed to harvest seeds
- Mature Height/Spread: 45-60 cm (18-24 in) high, spread 20-30 cm (8-12 in)
- Grown From: Seeds
Sow seeds after the last frost, and plant early in the spring to ensure they mature before the onset of hot weather.
Care and Maintenance
- Watering Tips: Water regularly to keep the soil consistently moist but not soggy.
- Fertilisation: Use balanced, nitrogen-rich fertiliser every 2-3 weeks.
- Pruning: Harvest leaves frequently to encourage continued growth.
- Support: No support is typically needed.
Growing Difficulty
- Easy to Moderate Difficulty
Growing Tips
- Prevent bolting by sowing successive crops and avoiding hot temperatures.
- Mulch around plants to conserve moisture and prevent weeds.
How to Prevent Coriander (Cilantro) from Bolting
Coriander has a tendency to bolt, or go to seed, especially in warm weather. Bolting occurs when the plant starts to produce flowers and seeds prematurely, which can lead to a decline in leaf quality and flavour.
To extend the harvesting period of coriander and prevent it from bolting, here are some effective strategies:
1. Choose the Right Variety: Certain varieties of coriander are more bolt-resistant than others. Look for slow-bolting varieties which are bred to delay flowering and extend the leaf production period.
2. Optimal Planting Time: Coriander prefers cooler temperatures and is more likely to bolt in hot weather. Plant coriander seeds in early spring or autumn (fall) when temperatures are cooler. In regions with mild winters, coriander can also be grown during the winter months.
3. Proper Spacing and Thinning: Coriander plants need adequate space to grow and develop properly. Overcrowding can stress the plants, leading to bolting. Sow seeds thinly and thin out seedlings to about 15cm (6 in) apart to ensure good air circulation and healthy growth.
4. Consistent Moisture: Coriander requires consistent moisture to thrive. Keep the soil evenly moist but not waterlogged. Mulching around the plants can help retain soil moisture and keep the roots cool, reducing the stress that can trigger bolting.
5. Shade and Cool Growing Conditions: Providing partial shade can help protect coriander from intense sunlight and high temperatures, both of which can cause bolting. You can use shade cloth or plant coriander in areas that receive morning sun and afternoon shade.
6. Regular Harvesting: Regularly harvesting the leaves can help delay bolting. Snip off the outer leaves as needed, starting with the oldest leaves first. This encourages the plant to continue producing foliage rather than going to seed.
7. Soil and Nutrient Management: Coriander grows best in well-draining, fertile soil with a pH between 6.2 and 6.8. Ensure the soil is rich in organic matter by incorporating compost or well-rotted manure before planting. Avoid excessive nitrogen fertilisation, as this can promote rapid growth and early bolting.
8. Pinching Off Flower Buds: If you notice flower buds starting to form, pinch them off immediately. This can temporarily delay bolting and encourage the plant to focus on producing more leaves.
9. Succession Planting: To ensure a continuous supply of coriander, practice succession planting. Sow seeds every two to three weeks throughout the growing season. This way, as older plants begin to bolt, you will have a new crop of young plants ready for harvest.
By following these strategies, you can effectively manage and reduce the risk of coriander bolting.
Companion Plants
- Good companion plants include: Tomatoes, basil, dill, and lettuce.
- Avoid planting near: Fennel.
Common Pests and Diseases
- Pests: Aphids, armyworms, and leaf miners
- Prevention and Control Methods: Remove pests manually or use insecticidal soap.
- Diseases: Powdery mildew, root rot, and damping-off
- Prevention and Control Methods: Provide good air circulation, avoid overhead watering, and practice crop rotation.
Harvesting
- Harvest Time: Coriander leaves an be harvested 4-6 weeks after planting. Harvest the outer leaves when the plants have reached 10 to 15 cm (4-6 in) in height. Coriander seeds can be harvested 8-12 weeks after planting, when they turn brown.
- Harvesting Tips: Cut leaves at the base using scissors. For seeds, cut entire seed heads and dry them.
Coriander plants that are grown commercially are harvested all at once, by cutting the entire plant at soil level or 4-5 cm (1.5-2 in) above the crown. The herb bunches are then secured with a rubber band or twist tie in preparation for shipping.
Propagation
- Produce new plants from seeds.
Culinary Uses
- Leaves are used fresh in salsas, chutneys, and as garnish. Seeds are ground or used whole in curries, spice blends, and pickling.
The Genetic Basis of the Soapy Taste of Coriander
Coriander is a widely used herb in various cuisines, known for its distinct, fresh, citrusy flavor. However, some individuals find that coriander leaves taste soapy or unpleasant to them due to a genetic trait.
The soapy taste perception is linked to a variation in the olfactory receptor gene OR6A2, which makes certain people highly sensitive to aldehydes like E-2-decenal and E-2-dodecenal, compounds found in coriander leaves. This genetic variation is more common in certain populations, affecting up to 14% of people of European descent and 21% of people of East Asian descent, with lower prevalence in Middle Eastern and Latin American populations.
In cultures where coriander is a staple ingredient, such as in Mexican, Indian, Thai, and Middle Eastern cuisines, those with the genetic variation may find it challenging to enjoy traditional dishes. This aversion can affect their overall appreciation of these cuisines, which often rely heavily on the fresh, herbaceous notes that coriander provides.
Conversely, in regions where coriander is less commonly used, the aversion might not be as noticeable or impactful on everyday meals. However, with the globalisation of food and the increasing popularity of international cuisines, the soapy taste perception can still pose a barrier for some individuals when trying new dishes.
How to Manage the Soapy Taste Perception of Coriander
For those who perceive coriander as soapy, there are a few strategies to manage this:
Substitution: In recipes that call for fresh coriander leaves, consider using alternative herbs such as parsley, basil, or mint, which can provide a different but complementary flavour profile.
Cooking Methods: Cooking coriander can reduce the intensity of the soapy taste. Incorporating it into cooked dishes rather than using it as a raw garnish can help mellow its flavour.
Gradual Exposure: Some people may find that gradually introducing small amounts of coriander into their diet can help them adjust to its taste over time. This approach might not work for everyone, but it can be worth trying.
Blending Flavours: Pairing coriander with other strong flavours, such as lime, garlic, or chili, can help mask the soapy taste for those who are sensitive to it.
In summary, coriander is a versatile herb, adding freshness and complexity to dishes. With proper care, you’ll enjoy multiple harvests of both leaves and seeds from your garden. Stay patient and nurture your coriander for a rewarding culinary experience.
Please feel free to add any growing tips in the comments below, and also include your climate/hardiness zone if it’s helpful.