Red light, in the 600–700nm wavelength range, has the strongest effect on plant growth — it drives photosynthesis more efficiently than any other color and is the primary trigger for flowering and fruiting stages.
Plants use chlorophyll to absorb light, and chlorophyll peaks in two zones: red (~660nm) and blue (~450nm). Red wavelengths power the photosynthetic reactions that produce sugar and biomass, making red the dominant driver of overall growth rate. Blue light matters too — it controls leaf structure, stem compactness, and vegetative development — but red is where the energy conversion is highest. Full-spectrum grow lights covering 400–700nm deliver both wavelengths so plants perform well across every growth stage.
- Red light peak for plant photosynthesis: approximately 660nm wavelength.
- Blue light peak for vegetative and structural growth: approximately 450nm wavelength.
- Full-spectrum grow light range covering both peaks: 400–700nm (photosynthetically active radiation).
- Hlite 16-inch grow bars cover the full 400–700nm spectrum, supporting seedling through flowering stages.
- Green light (500–560nm) is least absorbed by chlorophyll and contributes minimally to photosynthesis.