High Intensity Discharge, or HID grow lights, are a superd method to get the most growth and yeild out of your plants and have the longest life span and highest efficiency of any type of indoor lighting. When we talk about HID grow lights, we are referring to Metal Halide grow lights (MH), High Pressure Sodium grow
lights (HPS), as well as conversion grow lights. MH grow lights emmit light in the blue spectrum and are best used for the cloning and vegetative growth stages. HPS grow lights emit light in the red spectrum and are best used for
 the flowering growth stage. Conversion lights are pretty much a combination of HPS and MH grow lights, and emit light in both the red and blue spectrums
Fluorescent lights are adequate for plants that do not need much sunlight, but will not help produce anything other than greenery.

Using HID lights extends the growing season in the autumn and allows a head start in the spring, but don't get too carried away!   Extending the light beyond 18 hours a day will wear your plants out and cause an untimely demise

A 600 Watt HPS grow light is a great selection, not only for flowering plants, but for very nearly any type of indoor garden a person is wishing to grow. A unit of this size and nature is a type of HID or high-intensity discharge, light.
 Most indoor gardeners have always understood that these particular types of lights are about as close as a person can get to copying the beneficial rays of the sun. That is not to say, however, that a 600 Watt HPS grow light is not without its fair share of disadvantages
keep in mind is that a 600 Watt HPS grow light gives off a large amount of heat. If this light is placed too close to the plant canopy, they can burn, dry out, or even die completley. This is why many experts recommend that a person
 put a thermometer and an extract fan in the area where their garden is growing in order to more effectively regulate the temperature and remove heat. A hygrometer is also a great tool to measure humidity and temperature. This is especially important
 if the grow light is being used in a more confined area. This particular type of light may be the perfect choice if a person is trying to compensate for the cooler temperatures and heat up a room.

High performance lamps take indoor horticulture to the next stage By using colour enhancement technologies. You can now get bulbs that come very close to immitating normal sunshine.
All types of indoor grow light make use of what is known as a ballast . With MH and HPS grow lights, these are remote, meaning that an external box is required in order to house an electronic pre-heating system, which in turn runs the lamp itself
The remote idea is a good one making it possible to place the ballast away from your grow.