What are they? Plant grow or “agro” lamps are designed to maximize output in the areas of the spectrum most conducive to plant growth. They come in a variety of wattages, sizes, and finishes. How do they work? Plant grow lamps work by using phosphors and filtering agents in the glass enclosure to increase output in the areas of the spectrum most effective at encouraging plant growth. Plant grow lamps can be incandescent, fluorescent, HID, or LED. There are even more specific breakdowns within these lamp types which are designed to produce light for specific plants and/or specific stages of growth. Generally speaking, these lamps are designed to emulate daylight for the benefit of plants that are being grown indoors. Where are they used? Plant grow lamps are ideal for usage in areas being utilized to grow plants indoors, usually when sunlight is lacking, to supplement natural sunlight, or when it is desirable to usurp the natural cycle of sunglight in order to manipulate plant growth.