Coriander

Quick growing conditions

How to Grow Coriander Hydroponically at Home

Coriander (Coriandrum sativum), also called cilantro, is an annual herb grown for its aromatic leaves and seeds. In American English, “cilantro” usually means the fresh leaves, while “coriander” means the dried seeds.

Hydroponic coriander provides fresh leaves for cooking without soil. The main challenge is keeping plants leafy before they begin flowering.

Choosing a Variety

Choose a slow-bolting variety for leaf production. Suitable examples include Leisure, Calypso, Cruiser, and Santo.

Slow-bolting varieties delay flowering, but they can still flower early under high temperatures and long days. Santo was used in the hydroponic study supplying the nutrient profile below.

Main Growing Conditions

Temperature and lighting values are practical indoor starting points, not strict growth limits or a combination tested in the cited study. Lux readings depend on the lamp spectrum.

Coriander can grow in warmer conditions, but heat and long days encourage flowering. For fresh leaves, avoid overheating the plants and reservoir.

The nutrient study used approximately 22°C air and solution temperatures. This does not mean the solution must be heated to 22°C in a cooler room.

Choosing a Hydroponic System

NFT is suitable for coriander and was used in the cited study. Keep the solution circulating reliably and allow enough space for the roots.

An aerated deep-water system is another option for home growing. Keep the plant crown above the solution and maintain oxygen around the roots.

Cover the reservoir to limit algae and provide gentle airflow through the foliage.

Research Nutrient Profile

The following values reproduce the initial measured nutrient concentrations in the 1.0 mS/cm treatment under lower light in Currey, Walters, and Flax (2019), Table 2.

All concentrations are in mg/L of the finished nutrient solution. N is elemental nitrogen; P and K are elemental phosphorus and potassium.

Mo was not reported in the nutrient-analysis table. This does not mean it should be omitted from a complete fertilizer.

The researchers used a complete commercial hydroponic fertilizer supplemented with magnesium sulphate. The values above describe a measured research solution, rather than a complete fertilizer-mixing recipe or a universal optimum.

Recipe and profile source: Currey, Walters, and Flax (2019), “Nutrient Solution Strength Does Not Interact with the Daily Light Integral to Affect Hydroponic Cilantro, Dill, and Parsley Growth and Tissue Mineral Nutrient Concentrations”, Table 2 and Materials and Methods.

Use this profile as a starting point and modify it according to plant growth and your conditions. Account for nutrients already present in the water and use a complete micronutrient supply.

Measure EC after mixing. Different water and fertilizer salts can produce a different reading at similar elemental concentrations.

Use our NPK Calculator to formulate your nutrient solution.

Regular Care and Flowering

Check water level, pH, EC, and circulation regularly. Remove dead leaves and keep the crown dry.

Harvest outer leaves while preserving the central growing point. Avoid taking most of the foliage at once.

As coriander begins flowering, it produces taller stems and finer, fern-like leaves. Removing flower stalks does not permanently return the plant to leafy growth.

Coriander is an annual. Grow successive batches for a continuous supply rather than expecting one plant to produce leaves indefinitely.

Pollination is unnecessary for leaf production. If you want coriander seeds, allow flowering and seed development instead.

When and How to Harvest

Allow approximately six to eight weeks from seed for a useful leaf harvest. Variety, temperature, germination time, and lighting can change this schedule.

The hydroponic study evaluated plants approximately seven weeks from seed, after three weeks of initial development and four weeks in NFT.

Start picking when plants have enough foliage, typically around 10–15 cm tall. Cut outer leaf stems near their base and leave the centre intact.

For a bunch harvest, leave approximately 2.5–3 cm above the growing medium without damaging the crown. Healthy plants may regrow for another cutting.

Use leaves fresh for the strongest aroma. For seeds, harvest when the seed heads turn brown, then finish drying in a ventilated place.

Common Problems, Pests, and Diseases

• Early flowering: Reduce overheating and review lighting duration. Choose a slow-bolting variety and replace flowering plants when leaf production declines.
• Leafhoppers: Inspect plants, particularly after outdoor exposure. These insects can transmit aster yellows, which causes abnormal yellow growth and distorted flowers.
• Bacterial leaf spot: Isolate affected plants, avoid splashing water between plants, and clean cutting tools.
• Seedling collapse or root deterioration: Check cleanliness, aeration, circulation, and prolonged saturation around the crown.
• Weak or stretched growth: Check light coverage and overcrowding before increasing fertilizer strength.

For pesticide-free home growing, prioritise clean equipment, insect exclusion, physical pest removal, and suitable biological controls.

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Growing References

• Utah State University, Cilantro/Coriander in the Garden
• University of Wisconsin, Cilantro / Coriander

Sources

• Currey, Walters, and Flax (2019): Nutrient Solution Strength Does Not Interact with the Daily Light Integral to Affect Hydroponic Cilantro, Dill, and Parsley Growth and Tissue Mineral Nutrient Concentrations
• Utah State University: Cilantro/Coriander in the Garden
• University of Wisconsin: Cilantro / Coriander