Understanding PAR and DLI Needs for Cilantro (Coriander)

Cilantro (Coriandrum sativum) is a fast-growing, cool-season herb that’s as sensitive to light as it is to temperature. Managing its PAR (Photosynthetically Active Radiation) and DLI (Daily Light Integral) correctly ensures lush, flavorful leaves and delays bolting.

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1. Seedling Stage (Days 0–14)

Metric	Range	Notes
PAR (µmol·m⁻²·s⁻¹)	100–200	Gentle light encourages compact, sturdy seedlings.
DLI (mol·m⁻²·day⁻¹)	6–10	Avoid strong light that can dry out the soil or cause leaf burn.

Tips:

• Use diffuse light or filtered LED grow light at close distance.
• Maintain cool temperatures (18–22°C / 64–72°F) to prevent premature bolting.

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2. Vegetative Stage (Days 15–35)

Metric	Range	Notes
PAR (µmol·m⁻²·s⁻¹)	250–400	Supports rapid leaf growth and chlorophyll formation.
DLI (mol·m⁻²·day⁻¹)	12–18	Higher DLI promotes richer aroma and stronger stems.

Tips:

• Ensure consistent 12–14 hours of light per day.
• Monitor for signs of stretching — it means light is too weak.
• Avoid strong midday spikes if growing under sunlight; even light distribution is best.

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3. Harvest / Regrowth Stage (Days 35–60)

Metric	Range	Notes
PAR (µmol·m⁻²·s⁻¹)	300–450	Maintains dense leaf canopy and promotes regrowth after cutting.
DLI (mol·m⁻²·day⁻¹)	14–20	Keeps cilantro productive before flowering begins.

Tips:

• High PAR with long photoperiods (>14 hrs) can accelerate flowering—shorten day length slightly to prolong harvest.
• Rotate pots to ensure even light exposure.

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Light Management Summary

Growth Stage	PAR (µmol·m⁻²·s⁻¹)	DLI (mol·m⁻²·day⁻¹)	Objective
Seedling	100–200	6–10	Compact seedlings
Vegetative	250–400	12–18	Lush foliage
Harvest	300–450	14–20	Strong regrowth

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Why Monitoring PAR and DLI Matters for Cilantro

Cilantro’s productivity depends on stable, moderate light. Too little light produces pale, weak leaves; too much accelerates bolting.
By tracking PAR and DLI with tools like the AquaHorti AH-PARDLI Bluetooth PAR/DLI Logger, you can visualize light trends across days and seasons — ensuring your cilantro receives just the right amount of energy for leafy perfection.