One of the most frequently asked questions in indoor growing is LED spectrum selection. Red? Blue? Full spectrum? The answer is actually quite clear.
What plants need
Plants primarily use two wavelength ranges for photosynthesis: - Red (630–660 nm): Growth and flowering stage - Blue (440–470 nm): Seedling and vegetative growth stage
A red-blue only combination works, but the resulting "blurple" light is uncomfortable for eyes and makes it hard to assess plant health.
Why full spectrum is better
Full-spectrum LEDs mimic natural sunlight. The 75W Samsung MCPCB panel in GrowlyBox combines 3000K warm white, 6000K cool white, 630 nm red and 460 nm blue LEDs. This looks natural to the eye and gives the plant everything it needs across all growth stages.
CRI and PPF
- CRI (Color Rendering Index): 90+ CRI lets you accurately see plant color.
- PPF (Photosynthetic Photon Flux): Measured in µmol/s. 150–250 is ideal for lettuce, 400–600 for tomatoes.
GrowlyBox's LED panel comes with a PPF value optimized for its 35×35 cm cabinet footprint.