Controlling light levels

• The amount of light intensity needed in a greenhouse depends on the plant. Intensity of available light is measured in foot-candles (f.c.), which range from 500 f.c. on an overcast winter day to 10,000 f.c. on a clear summer day.
• Environmental factors that affect light intensity are geographic location, season, time of day, pollution, and cloud cover
• Light intensity can be read by a light meter or a computerized photocell.
• Light intensity can be increased or decreased to meet the plant’s requirements.
• Light intensity/day length can be increased with supplemental lights such as fluorescent lights or high-intensity discharge lights.
• Using black material to block plants from light decreases light intensity/day length.
• Putting plants under a bench reduces exposure to light.
• Spraying a shading compound on the growing structure and placing a shade cloth above plants or over the growing structure also decrease light intensity.