Marijuana Horticulture: The Indoor/Outdoor Medical Grower's Bible

electricity.
    Any unused light is wasted. There are several ways to get the most out of your light without adding more watts, including:
         Use several 400 or 600-watt lamps instead of 1000’s.
         Manually rotate plants regularly.
         Add a shelf.
         Install rolling beds.
         Grow a perpetual crop.
         Use a light mover.
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    Reflective Mylar provides one of the most reflective surfaces possible. Mylar looks like a very thin mirror. Unlike light-absorbing paint, Reflective Mylar reflects almost all light. To install Reflective Mylar, simply tape or tack to the wall. To prevent rips or tears, place a piece of tape over the spot where the staple, nail or tack will be inserted. Although expensive, Mylar is preferred by many growers. The trick is to position it flat against the wall. When loosely affixed to surfaces, light is poorly reflected. To increase its effectiveness, keep Reflective Mylar clean.
    Aluminum foil is one of the worst possible reflective surfaces. The foil always crinkles up and reflects light in the wrong directions-actually wasting light. It also reflects more ultraviolet rays than other surfaces, which are harmful to chloroplasts in leaves.
    Mirrors also reflect light, but much less than Mylar. Light must first pass through the glass in the mirror, before it is reflected back through the same glass. Light is lost when passing through the glass.

Move small plants to shelves around the perimeter of the grow room. Remember, plants grow wherever light shines!
More Free Growing Light
    Even though the lumens-per-watt conversion is lower with 400-watt bulbs than 1000-watt bulbs, hanging ten 400-watt lamps over the same area that four 1000-watt lamps cover, provides more even distribution of light and minimizes shading. Three 600-watt lamps that produce 270,000 lumens from three point sources, instead of two 1000-watt HP sodiums yielding 280,000 lumens from two points, lower total light output by 10,000 lumens, but increases the number of sources of light. Lamps can be placed closer to plants, increasing efficiency even more.
    Manually rotating plants helps them fill out better, promoting more even development. The longer plants are in the flowering growth stage, the more light they need. During the first three to four weeks of flowering, plants process a little less light than the last three to four weeks. Plants flowering during the last three to four weeks are placed directly under the bulb where light is the brightest. Plants that have just entered the flowering room can stay on the perimeter until the more mature plants are moved out. This simple trick can easily increase harvests by five to ten percent.
    When plants get big, it can become laborious to rotate them. Difficult jobs often go undone. Save the strain and use a light mover, or put the containers on wheels.
    Add a shallow shelf around the perimeter of the garden to use light that is eaten by the walls. This sidelight is often very bright and very much wasted. Use brackets to put up a four to six-inch-wide shelf around the perimeter of the garden. The shelf can be built on a slight angle and lined with plastic to form a runoff canal. Pack small plants in six-inch pots along the shelf. Rotate them so they develop evenly. These plants can either flower on the short shelf or when moved under the light.
    Installing rolling beds will remove all but one walkway from the garden. Greenhouse growers learned long ago to save space. We can use the same information to increase usable grow space in a grow room. Gardens with elevated growing beds often waste light on walkways. To make use of more growing area place two, two-inch (6 cm) pipes or wooden dowels below the growing bed. The pipe allows the beds to be rolled back and forth, so only one walkway is open at a time. This simple trick usually increases growing space by about 25 percent.
    Growing a perpetual crop and flowering only a portion of the garden allows for more plants in a smaller area and a higher overall yield. More plants receive intense light, and no light is wasted in such a garden.

Reliable linear light movers offer an exceptional value to indoor growers. Light intensity increases exponentially when bulbs are moved closer to the garden using a light mover.

A single light mover transports all four 1000-watt HP sodium lamps over this rockwool garden of flowering females.
     
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Benefits of a light mover:
    Bulbs can be placed closer