"What grow light is best for me?" and "What is the best growlight?" are questions we are asked regularly. Unfortunately there is no one size fits all answer to which is the best type of grow light.
Grow lights come in a variety of shapes, sizes, types & wattages. Many factors will be considered prior to selecting a light that works best for your grow space. Indoor grow operations will require far more light than a green house or out door grow operation. Indoor growers must provide 100% of the primary light through artificial lighting whereas greenhouse & outdoor growers only require supplemental lighting (if any). With so many grow lights on the market today to choose from, growers can find a light that fits their needs perfectly.
Several popular forms of horticultural lighting are HID (High Intensity Discharge) Lighting, HPS (High Pressure Sodium), MH (Metal Halide), fluorescent (T5, T8, T12, HO & VHO) lighting, LED Lights, CMH (Ceramic Metal Halide) & LEC (Light Emitting Ceramic) Lights, CFL (Compact Fluorescent), LEP (Light Emitting Plasma), DE (Double Ended) Grow Lights, A/C (Air Cooled & Air Coolable), Wing Reflectors, Lamps, Bulbs, Digital & Electronic Ballasts, Magnetic core & coil ballasts, light movers & rails, timers, flip boxes, lighting controllers, complete de fixtures and induction lights. Each light serves a different purpose better than the next. An outdoor or green house grower would only need enough light to interrupt the dark period of the plant to keep it in a prolonged vegetative state. Indoor growers require many more grow lights to achieve adequate levels of light intensity in order to provide sufficient par readings to the canopy. Lights should be positioned to spread and disburse the light as evenly and efficiently across the grow room as possible. Different strains or strands of plants require different levels of light to maintain optimal growth. Propagation, cloning & popping seeds is usually done with a soft light such as a fluorescent. People often place T-5 fixtures or CFL lamps directly on top of their bubbleponic cloning machine or cloner dome. Once seedlings or cuttings have matured and begin the vegetative stage many people switch the MH bulbs or CMH lamps which put off light usually starting in the blue (10,000 kelvin) spectrum and up to 4K. Metal Halide lamps promote tight, lateral growth and short internodal spacing which produces a plant with more bud sites. When switching your plants to bloom, growers will generally use lights in the red spectrum such as hortilux HPS &, lamps around 2k to 3 kevlin. Bulbs in the red spectrum are used to induce a large and heavy bloom and used throughout the bulking stage of the plants life. For the ripening or "finishing" or "final" phase, some growers elect to switch back to deep blue lighting to mimic winter approaching and in an effort to stimulate the plants to ripen fully.
Also be sure to purchase the correct voltage as grow lights come in several different volts including 110, 120, 220, 240, 277, 347, & 477. Additionally, LED lights come in 1, 2, 3, 4 & 5 w diodes.