Fluorescent lamps have gone through major changes in recent years. New bulbs produce more light. Most growers use fluorescents lo grow clones and small vegetative plants and maintain mother plants. Some growers even use them to flower a crop. Fluorescents are available in many different speclrums, some almost identical to natural sunlight.
Fluorescent lamps are long glass tubes that come in a wide variety ol lengths, from one to twelve feet, The two- and four-foot tubes are the easiest to handle and most readily available. Two four-foot fluorescent bulbs in a shop light fixture cost from $20 to $30.
Fluorescent lamps work very well for root cuttings. They supply cool, diffused light in the proper color spectrum to promote root growth. Use any "daylight spectrum" fluorescent lamp to root cuttings. Fluorescents produce much less light than HID's and must be very close (two to four inches) to the plants for best results.
Using fluorescents along with HID's is awk ward and problematic. When using them in conjunction with HID's, lluorescents must be very close to plants to provide enough intense light to do any good. Fixtures may also shade plants from HID light and generally get in the way.
Plants will flower under fluorescent lights. The buds will be small and light, but, with enough fluorescent light, you can grow a mature crop. The grow show will have to literally be lined with fluorescents.
Fluorescent tubes are available in so many different wattages or outputs that they are hard to track! All fluorescents require specific ballasts. The old standard (T12) tubes use about 10 watts per linear foot. A two-foot tube uses about 20 watts, four-foot: 40 watts, etc. The most common bulbs used for growing are available in lengths from 15 inches (38 cm) to four feet (120 cm). Lamps are available in very low to more than 50 watts. Circular fluorescent tubes are also available but used by few growers.
Power twist, or groove type, lamps offer additional lumens in the same amount of linear space. The deep wide grooves give more glass surface area and more light output. Several companies market variations of power twist fluorescents.
Black light fluorescent lamps emit ultraviolet (UV) rays through a dark filter glass bulb, but they are not used to grow cannabis, Ultraviolet light is supposed to promote more resin formation on buds. However, all known experiments that add artificial UV light in a controlled environment have proven that it does not make any difference.
Most of the major lighting manufacturers-GE, Osram/Sylvania, and Philips-make fluorescent lamps in a variety ol spectrums. The most common are Warm White, White, Cool White, Full Spectrum, and Daylight, See chart for Kelvin temperatures. Sylvania has the GroLux and the Wide Spectrum GroLux. The Standard GroLux is the lamp to use for starting clones or seedlings. It is designed for use as the only source of light, having the full spectrum necessary for photosynthesis and chlorophyll production. The Wide
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