How High Should Grow Lights Be Above Seedlings?
Grow lights should be kept fairly close to seedlings, but not too close or they will burn the delicate young seedlings. The optimal spectrum for seedling growth is one rich in blue wavelengths, which promote strong, compact growth.
For LED grow lights, start with the lights about 2-2.5 feet (60-75 cm) above the seedlings when they first sprout. As the seedlings grow taller, you can lower the lights to around 1-1.5 feet (30-45 cm) above the tops.
For fluorescent lights, have them 4-6 inches (10-15 cm) above the seedlings at first, then raise the lights up to 2-4 inches (5-10 cm) from the top as the plants grow.
For high intensity lights like metal halide or sodium, keep them 2-3 feet (60-90 cm) above when seedlings first come up, lowering to 1-2 feet (30-60 cm) away later on.
For LED grow lights, start with the lights about 2-2.5 feet (60-75 cm) above the seedlings when they first sprout. As the seedlings grow taller, you can lower the lights to around 1-1.5 feet (30-45 cm) above the tops.
For fluorescent lights, have them 4-6 inches (10-15 cm) above the seedlings at first, then raise the lights up to 2-4 inches (5-10 cm) from the top as the plants grow.
For high intensity lights like metal halide or sodium, keep them 2-3 feet (60-90 cm) above when seedlings first come up, lowering to 1-2 feet (30-60 cm) away later on.
