Separate time from light quantity
Photoperiod is the length of the light period. Intensity describes light arriving at the plant at a particular moment; daily light integral adds it up over the day. A weak lamp does not become equivalent to a strong one just because both run for the same number of hours.
Further reading: University of New Hampshire Extension · Growing seedlings under lights
Distance changes what leaves receive
Light reaching a plant changes with lamp distance. Use the fixture’s recommended positioning and raise an adjustable lamp as directed when plants grow. Check the whole canopy, not only its tallest leaf. Do not copy a distance from a different lamp or assume a purple glow proves adequate output.
Further reading: University of New Hampshire Extension · Growing seedlings under lights
Observe before making a change
Stretching or leaf discoloration can prompt a closer look, but neither is a diagnosis by itself. Check lighting alongside water, nutrition and the crop’s requirements. More light is not always better. Keep the recommended dark period and record one adjustment at a time.
Further reading: University of Minnesota Extension · Lighting for indoor plants
Sources & further reading
Original GrowGrid explanations informed by university extension guidance. The linked guides describe different growing systems; they do not endorse GrowGrid products.
