PAR & DLI Requirements for Exotic Greens at Different Growth Stages

Exotic greens—such as mizuna, pak choi, tatsoi, mustard greens, arugula, and komatsuna—are fast-growing, nutrient-dense leafy crops widely cultivated in hydroponic and greenhouse systems.
Their productivity and flavor strongly depend on maintaining the right PAR (Photosynthetically Active Radiation) and DLI (Daily Light Integral) through each growth phase.

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1. Germination / Seedling Stage

Metric	Typical Range	Notes
PAR (µmol·m⁻²·s⁻¹)	100 – 180	Gentle light encourages even sprouting and prevents leggy seedlings.
DLI (mol·m⁻²·day⁻¹)	6 – 10	Low DLI avoids stress before roots and cotyledons mature.

Tips

• Use cool-white or balanced spectrum LEDs.
• Keep relative humidity > 80 % for uniform emergence.
• Avoid long photoperiods; 14 – 16 hours is ideal for seedlings.

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2. Vegetative / Leaf Development Stage

Metric	Typical Range	Notes
PAR (µmol·m⁻²·s⁻¹)	250 – 450	Promotes rapid leaf expansion and chlorophyll accumulation.
DLI (mol·m⁻²·day⁻¹)	12 – 18	Supports dense canopies and enhances nutrient density.

Tips

• Moderate blue-light content (10 – 20 %) keeps leaves compact.
• Increase DLI gradually as canopy thickens to maintain uniform photosynthesis.
• Ensure good airflow to prevent tip burn under high light.

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3. Mature / Harvest Stage

Metric	Typical Range	Notes
PAR (µmol·m⁻²·s⁻¹)	400 – 600	High PAR boosts carbohydrate storage and pigment formation.
DLI (mol·m⁻²·day⁻¹)	18 – 25	Improves flavor intensity and post-harvest shelf life.

Tips

• Use full-spectrum light with a red:blue ratio of about 4:1.
• Avoid sudden light drops before harvest; it reduces vitamin C and nitrate metabolism.
• For multi-cut systems, maintain constant DLI to encourage regrowth.

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Quick Reference Table

Growth Stage	PAR Target	DLI Target	Key Focus
Seedling	100–180 µmol·m⁻²·s⁻¹	6–10 mol·m⁻²·day⁻¹	Uniform germination & root initiation
Vegetative	250–450 µmol·m⁻²·s⁻¹	12–18 mol·m⁻²·day⁻¹	Leaf area & chlorophyll build-up
Mature / Harvest	400–600 µmol·m⁻²·s⁻¹	18–25 mol·m⁻²·day⁻¹	Flavor quality & yield

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Why Tracking PAR and DLI Matters for Exotic Greens

Because exotic greens grow rapidly—often harvestable in 20–30 days—even small light imbalances can reduce color vibrancy and yield.
Continuous PAR / DLI logging reveals:

• Midday dips caused by shading or light angle changes
• Daily DLI trends for different greenhouse sections
• Correlations between light supply and nutrient uptake

With an AquaHorti AH-PARDLI Bluetooth Logger, growers can:
✅ Record 180 days of PAR and DLI data automatically
✅ View light curves directly on a smartphone—no Wi-Fi required
✅ Export CSV files for growth analysis and yield optimization