Horticulture Lighting
Many cultivators wish to grow their plants indoors in the privacy of their own home. Growing plants indoors can be difficult due to limited access to enough sunlight. Many advances have been made in horticulture lighting recently making indoor gardening possible year round. It is now possible to so closely duplicate the natural light energy required by plants that an entire crop can be produced without ever actually seeing natural sunlight.
Advanced cultivators can actually mimic natural sunlight and seasons using artificial lighting. Have you ever wondered how garden centers and flower shops always have out of season blooms and beautiful orchids in mid-winter? Most flowering plants have three main stages: seedling, vegetative and flowering/fruiting. The last stage is initiated by changes in the season including temperature, light intensity, spectrum and duration.
Light intensity is usually measured in watt per square foot. 20-50 watts per square foot is optimal. Lights should be suspended above your plants on an adjustable stand. Heat from your lights can damage your crop so keeping them at a safe distance is important. The higher the power, the further your light should be from your plants unless using a light mover which limits exposure allowing your plants to cool. The optimum distance from your light source to your plant should be: 12-14” for a 250 watt bulb, 16-24” for a 400 watt bulb and 2' minimum for a 1000 watt system.
A simple inexpensive timer can be used to automate your lighting system. It is a valuable low cost investment that will be necessary for creating proper light cycles.
A light meter can be a valuable tool for insuring an evenly and properly lit area.
Your growing area should be finished with a semi-flat white paint or highly reflective mylar sheeting. Aluminum foil can be used although it is actually less reflective than flat white paint. If the surface is not paintable for some reason and/ or of a dark color, aluminum foil is a cheap alternative and would be well worth the effort.
Lighting duration should be 16-18 hours per day. Anything more than 18 hours is pointless. For force flowering, plants should be exposed to 12-14 hours of light a day. Complete darkness is required for flowers and fruits to form correctly. This can be maintained by simply timing your lights to shut down at night and power up during the day.
I have been experimenting with outdoor HID lighting units, purchased from Home Depot, as a lower cost supply for HID lighting. Although most of the units they sell are actually more expensive, I did find a 50 watt HPS unit for $20 on sale which I now use for additional red light. Other sources for affordable lighting are non-profit donation based home building centers, like Habitat for Humanity. I've found HPS bulbs and outdoor lighting units at flea markets as well. I've also seen outdoor HID lighting systems at auctions, and in case you wanted to know, a lot of outdoor commercial lighting and street lighting is HID lighting.
Compact florescent lighting is kind of a touchy subject when it comes to indoor horticulture lighting. Although incredibly efficient, they do not produce enough photosynthetically active radiation to achieve the desired results.
All lighting units need to be vented to keep your growing area at the proper temperature. Most units come with built in ventilation in which a fan can be used with 4” LAMA Flexible tubing, commonly used for venting clothes drying machines.
