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How Many Lumens Grow Light for Cannabis?


May 23, 2024

Probably the most common question we get for LED grow lights. The ideal amount of light for growth of different types of plants is below: Cannabis is 7150 lumens (65 watts) per 2 square foot. Lumens aren't the ideal metric for measuring grow lights for cannabis. Recommendations for cannabis vary - Depending on the growth stage (vegetative or flowering) and strain, cannabis thrives under PAR levels between 500-750 μmol/m²/s.

Plants use light for photosynthesis, Cannabis plants primarily use light in the Photosynthetically Active Radiation (PAR) spectrum (400-700 nanometers) for growth. Lumens measure total visible light output, which includes wavelengths beyond the PAR range that don't contribute to plant growth.

Focus on PAR instead, Grow light manufacturers typically specify their lights' output in micromoles per square meter per second (μmol/m²/s) within the PAR range. This directly relates to the amount of usable light for plant growth.

Grow Light for Cannabis

Grow Lights PAR Value for Marijuana Cultivation

What is PAR?

PAR stands for photosynthetically active radiation and refers to the wavelength range of 400-700 nanometers in the spectrum. Light in this range is crucial for photosynthesis in plants. Plants use photosynthesis to convert light energy into chemical energy to provide nutrients for their own growth and development.

Why is PAR value more important than lumens?

Lumen measures the total visible light output of a light source, including light outside the PAR range that does not contribute to plant growth. Therefore, the PAR value better reflects the effectiveness of the grow light on plant photosynthesis.

What PAR values are needed for cannabis cultivation?

The PAR values required for cannabis cultivation depend on the growth stage and variety. Generally speaking, the recommended PAR value range is: seedling stage - 200-300 μmol/m²/s, growth stage - 400-500 μmol/m²/s, flowering stage - 600-700 μmol/m²/s.

How to choose the right grow light PAR value?

When choosing a grow light, you need to pay attention to the planting area - determine the planting area so that you can calculate the total PAR value required. Plant Varieties - Different varieties of cannabis may have different requirements for PAR values. Grow Light Efficiency – Choose high-efficiency grow lights to maximize the use of light energy. Mounting Height - Follow your grow light's instructions to determine the appropriate mounting height to ensure even lighting.

About the author

TUBU is an expert in LED light research with more than 10 years of experience in this field. We hope that through our TUBU research, LED lighting technology will become more popular and bring greater convenience and comfort to people's lives.

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