The article below will explain the differences between High Pressure sodium Grow Lights and Metal Halide Grow Lights
Thinking about a little indoor gardening this winter? Whether you want healthy salad greens, tasty herbs or flowers in the gray of winter, consider growing some plants inside. Gardening–inside, outside, greenhouse, hydroponic and container–has taken off in recent years. People looking at high grocery bills have begun planning to grow their own produce. Unless you have lots of south-facing windows, though, or an enclosed porch that you could turn into a semi-greenhouse, you might need some extra lights. Many indoor gardeners are looking into high intensity discharge (HID) light to bolster production and harvest.
HID lighting systems contain a properly matched transformer, capacitor and lamp, which is an inner arc tube with a chemical mixture. The transformer and capacitor takes the input current and converts it, along with the starting pulse, into the operating voltage for each lamp. These lamps are energy efficient and long lived.
The two best HID lights for indoor gardening are high pressure sodium (HPS) and metal halide (MH). Each type of light has strengths and weaknesses. To plan a good indoor gardening system, it is important to learn about all the types of lighting available, and to research what lighting would work best for your purposes.
High Pressure Sodium Lights
High Pressure Sodium light bulbs emit a white light concentrated in the orange/red spectrum. The orange/red sector of the spectrum enhances plants’ reproductive processes. High Pressure Sodium simulates outside autumn light and plants respond by producing larger harvests of high quality fruits, vegetables and flowers. High Pressure Sodium, then, is used by indoor gardeners during the flowering and fruiting stage of plant life. When used alone throughout the plants’ life cycle, however, High Pressure Sodium causes plants to stretch and become leggy, with larger spacing between branches. Nevertheless, plants thrive under High Pressure Sodium lighting.
High Pressure Sodium bulbs have another benefit: a long usable bulb life, as long as two to five years, and they are very energy efficient with six times more light output per watt than an incandescent bulb. High Pressure Sodium lamps are the preferred light for supplemental greenhouse light. One caution: HID bulbs contain mercury, a hazardous material. Use caution when handling HID bulbs.
Metal Halide Lights
Metal halide lights give off an intense, bluish-white light that plants respond to with healthy, vigorous growth. Plants will be stocky and strong, with dense green foliage. Metal Halide is the light of choice for indoor plant gardeners. The downside to Metal Halide lights is that the light is poor in the orange/red part of the spectrum. Special Metal Halide lights created for horticultural now come with an enhanced red spectrum, the spectrum used by plants for producing fruit. Check before purchasing to be sure the Metal Halide bulbs are for indoor gardening.
Metal halide grow lights are about five times as energy efficient as an incandescent bulb, with a usable life span of about two years of 18/hour daily use. Keep track of the bulb’s life so it can be replaced before it loses intensity. Metal Halide bulbs are also HID, so handle with care.
Indoor gardening supply shops now have HID conversion bulbs so growers can have the benefit of both HPS and MH light. With a conversion bulb, it is possible to run a MH bulb from the sodium ballast or a sodium bulb from the halide ballast. Run the halide during the vegetative stage of the plants’ life, then switch to a sodium conversion bulb to stimulate a great harvest.