<P> A switchable ballast is an HID ballast can be used with either a metal halide or an HPS bulb of equivalent wattage . So a 600W Switchable ballast would work with either a 600W MH or HPS . Growers use these fixtures for propagating and vegetatively growing plants under the metal halide, then switching to a high - pressure sodium bulb for the fruiting or flowering stage of plant growth . To change between the lights, only the bulb needs changing and a switch needs to be set to the appropriate setting . </P> <P> LED grow lights are composed of light - emitting diodes, usually in a casing with a heat sink and built - in fans . LED grow lights do not usually require a separate ballast and can be plugged directly into a standard electrical socket . </P> <P> LED grow lights vary in color depending on the intended use . It is known from the study of photomorphogenesis that green, red, far - red and blue light spectra have an effect on root formation, plant growth, and flowering, but there are not enough scientific studies or field - tested trials using LED grow lights to recommended specific color ratios for optimal plant growth under LED grow lights . It has been shown that many plants will grow normally if given both red and blue light . However, many studies indicate that red and blue light only provides the most cost efficient method of growth, plant growth is still better under light supplemented with green . </P> <P> White LED grow lights provide a full spectrum of light designed to mimic natural light, providing plants a balanced spectrum of red, blue and green . The spectrum used varies, however, white LED grow lights are designed to emit similar amounts of red and blue light with the added green light to appear white . White LED grow lights are often used for supplemental lighting in home and office spaces . </P>

Do red and blue led grow lights work