| Metal halide grow lights create fantastic | | | | these lamps have an 80 color-rendering index, |
| light under which your plants will thrive. | | | | on a scale of zero to 100. This index ranks |
| These grow lights are a HID, or | | | | lights to show how well or poorly they |
| high-intensity discharge, light. They are | | | | reproduce colors of objects being lit by the |
| small grow lamps that produce a lot of light, | | | | lamp. |
| and yet are more efficient to run than either | | | | |
| incandescent or fluorescent light bulbs. | | | | 100 is the best rating, and zero the worst. |
| Indoor gardeners and hydroponics enthusiasts | | | | Therefore, an 80 is reflective of a very good |
| get great results with their plants when they | | | | quality white light. In terms of correlated |
| use metal halide lights. | | | | color temperature, MH grow lights can range |
| | | | from 3,000 K to 20,000 K. 3,000 is in the |
| Metal halide lamps are made up of several | | | | yellow range of the spectrum, while 20,000 is |
| different parts. There are tungsten | | | | in the blue range. (K refers to the Kelvin |
| electrodes which are connected to a quartz | | | | temperature scale.) In terms of comparison, |
| arc tube, where the light is produced. | | | | daylight registers in at 6,500 K, whereas a |
| Inside the arc tube is where you will find | | | | television screen is at 9,300 K and moonlight |
| mercury vapor, different metals and noble | | | | is at 4,100 K. If you are an indoor |
| gas, all of which play a part in creating the | | | | gardener, you are trying to recreate daylight |
| light produced by MH grow lights. The arc | | | | in order for your plants to thrive, so you |
| tube is covered by a glass bulb. There is a | | | | will want a bulb as close to daylight's 6,500 |
| metal base, and a connection to the power | | | | K as possible. |
| source. Some metal halide grow lights use an | | | | |
| arc tube made of alumina or aluminum oxide, | | | | Light produced by a grow lamp can fall at |
| as well. This type of grow light requires | | | | different spots on the electromagnetic |
| the use of a ballast to control the flow of | | | | spectrum. Some lights lean more toward the |
| the current through the arc tube in order for | | | | blue end of spectrum, while others land on |
| the grow lamp to function properly. | | | | the orange and red end. This matters to the |
| | | | indoor gardener, because baby plants need |
| Each different type of grow light has a | | | | light in the blue spectrum in order to grow |
| particular color-rendering index and | | | | well. If you want a mature plant to produce |
| correlated color temperature. This is true | | | | fruit or flowers, then you will need lights |
| of the metal halide grow lights. Some of | | | | in the red and orange spectrum. |