 Horticultural CDM offerings from companies such as Philips have proven to be effective sources of growth light for medium-wattage applications.Combination HPS/MH lights combine a metal halide and a high-pressure sodium in the same bulb, providing both red and blue spectrums in a single HID lamp.The combination of blue metal halide light and red high-pressure sodium light is an attempt to provide a very wide spectrum within a single lamp.