Light intensity is commonly measured in power (watts) per square foot. For optimal photosynthesis to occur a general rule of thumb is 20-50 watts per square foot, with 20 being best for low-light plants and 50 best for light loving plants. Maintain 250W HID lamps 12-14" from plants, 400W lamps should be from 1624" and 1000W lamps a minimum of 24" from plants unless your lamps are suspended by a circular or linear light mover in which case you may decrease the lamp to plant distance by 25-50%. To increase light effectiveness, paint your growing area with a semi-flat white paint sometimes referred to as an eggshell finish. The minimal gloss in this type of paint will provide maximum diffusion while still allowing you to wipe clean any smudges or stains that may appear in time. Other wall treatments include;
Mylar 90-95% reflective Flat white paint 75-80% reflective Gloss white paint 70-75% reflective Yellow paint 65-70% reflective Aluminum foil 60-65% reflective Black <10% reflective.
Was this article helpful?