Lamp height is the height between the lamp and the top of the plant. The amount of light determines the yield. The effect of a lamp at 20 inches is four times stronger than a lamp at 40 inches.

Learn all about growing and lighting:

• The Cannabis Light Cycle
• Control Your Lighting, Control Your Cannabis

More lighting related terms:

Lighting | Light cycle | Dark cycle | Light shortage | Light distribution | Light spectrum | Blue light | Red light | Nanometer | Light tight | Lumen | Lux | Reflecting light |

HPS lights | HPI lights | LED lights | Compact fluorescent lights