Discover our selection of metal halide (MH) lamps. Light produced by metal halide (MH) lamps is currently the most efficient source of artificial white light available to horticulturists. MH growth lamps emit a high percentage of blue light which promotes rooting and results in less stretched plants. They are therefore recommended for the vegetative period. However, if the outer glass of the bulb breaks, the lamp should be turned off and unplugged immediately and never look at or approach the bulb while it is hot: the broken protective glass no longer protects against ultraviolet light. All HDI lamps need a ballast, so it is very important to buy the right ballast for the lamp model, which is why they are usually sold in kits. You can find all the lamps for plants on our store. And get additional information and answers to your questions by asking it on the site.