Photosynthetically Active Radiation (PAR) is a term that you'll often hear in the world of indoor gardening and grow lights, and it refers to the range of light wavelengths that is most important for photosynthesis.

In other words, it's the spectrum of light that plants need to grow and thrive. Typically, PAR is defined as the range of wavelengths from 400 to 700 nanometres, which includes colours that are visible to the human eye, such as red, orange, yellow, green, and blue.

However, PAR range is not just limited to photosynthesis, it plays a crucial role in other essential plant processes, such as flowering.

Different wavelengths of light can affect plant growth and development in different ways. For example, research reveals that red and blue light have different effects on plant growth and development, with blue light generally promoting vegetative growth and red light promoting flowering. Interestingly, despite blue light emitting more energy, it's the red light that steals the show, generating photosynthesis with higher efficiency. However, the full spectrum is important for healthy plant growth.


Do plants use Green light? As some grow lights cut out green light and look purple.

Small amounts of green light are beneficial to plants as it penetrates deeper into the leaf canopy, allowing lower leaves to thrive. Research indicates that green light affects certain aspects of plant development, such as leaf expansion. Incorporating green light in grow lights ensures that the light spectrum is closer to a plant's natural outdoor environment.


But, how can we determine the ideal amount of PAR light for our plants?

Enter the Daily Light Integral, our beacon of light in the pursuit to provide perfect conditions for our flourishing indoor gardens. It is a measure of the total amount of Photosynthetically active radiation (PAR) that a plant receives in 24 hours.


💡 Key Takeaway: Photosynthetically Active Radiation (PAR) is the range of light wavelengths (400-700 nm) essential for photosynthesis.

Written by Lorenzo Cadoux-Hudson

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