PAR & DLI Requirements for Mint at Different Growth Stages

Mint is a resilient, aromatic herb often grown in greenhouses, herb gardens, and indoor farms. It tolerates a range of light conditions, but providing the right PAR (intensity) and DLI (daily light integral) can boost leaf yield, essential oil content, and overall plant health. Below is a guideline for mint’s light needs during its growth cycle, along with practical tips.

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1. Germination / Early Seedling Stage

Metric	Typical Range	Notes
PAR (µmol·m⁻²·s⁻¹)	80–150	Gentle light to support leaf and root establishment
DLI (mol·m⁻²·day⁻¹)	5–10	Sufficient for low-light-tolerant seedlings

Tips:

• Use diffused, cool-spectrum LED or fluorescent lighting.
• Maintain moderate distances to reduce hotspots or leaf burn.
• Grow in slightly cooler temperatures (~18–22 °C) for stronger initial growth.

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2. Vegetative / Leaf Growth Stage

Metric	Typical Range	Notes
PAR (µmol·m⁻²·s⁻¹)	250–400	Encourages robust leaf production and branching
DLI (mol·m⁻²·day⁻¹)	12–20	A balanced daily light supply to maximize leaf yield

Tips:

• Use a spectrum rich in green + some blue and red light to maintain balanced foliage color and growth.
• Ensure even light distribution across the canopy; mint can become leggy under uneven light.
• Trim lower leaves or train stems to prevent shading within the plant mass.

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3. Mature / Harvest Stage

Metric	Typical Range	Notes
PAR (µmol·m⁻²·s⁻¹)	350–550	Higher intensity helps maintain leaf vigor and essential oil synthesis
DLI (mol·m⁻²·day⁻¹)	18–28	High daily light integral to support full growth and aroma development

Tips:

• During cloudy days or winter, use supplemental lighting to maintain DLI.
• Avoid overheating—mint prefers moderate temps under high light.
• Harvest leaves regularly to stimulate new growth and maintain quality.

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Quick Reference Table

Growth Stage	PAR Target	DLI Target
Seedling	80–150 µmol·m⁻²·s⁻¹	5–10 mol·m⁻²·day⁻¹
Vegetative	250–400 µmol·m⁻²·s⁻¹	12–20 mol·m⁻²·day⁻¹
Mature / Harvest	350–550 µmol·m⁻²·s⁻¹	18–28 mol·m⁻²·day⁻¹

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Why Mint’s Light Requirements Vary

• Mint is naturally shade-tolerant, so its light needs are lower than fruiting crops.
• Leaf quality and oil content respond positively to higher light, but the plant can tolerate moderate conditions.
• Environmental factors—temperature, nutrients, spacing, airflow—must align with light levels for optimal results.

Using a PAR/DLI logger like AH-PARDLI can help track real conditions, verify whether your light setup meets these targets, and fine-tune for better mint growth and flavor.