Where should lights be placed in relation to plants?

Lights should be hung directly above, the distance from the fluorescent tubes varying from 6 to 15 inches, depending on the size and type of plants. With adjustable chains or flexible arms, lights can be moved up and down as necessary to control growth. Incandescent lights must be hung higher—at least 24 inches above plants—because they give off a great deal of heat which may be harmful. Fluorescents, on the other hand, are “cool” lights.