Cheers !!sara . .Morning and evening Kingjoe.
During flowering stage we ususally recommend 12"-18",but you can hang it closer,some grower keep it around 14"-16" above the plants.You can make adjustment according to their react,usually plants love more lights.As long as they didn't get stress or light burn.
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King's True Grow - Autos - LED - 900 - Tent - Pro Mix