Robertsanswered grow question 3 years ago Start at least 3 foot and move closer as days go by. If you have a way to measure light intensity that would make it easier to adjust appropriately. Every plant and light has a sweet spot, leaves will stand straight out and up but be flat if you get it in range. Plant will be super happy. That is later in your grow. For now just watch if plant is stretching as seedling. If it is move closer