High intensity discharge lamps are easier to use, and more efficient. Low wattage HID's are sometimes sold for household outdoor use. Large Wattage lamps are used for lighting streets, parking lots, stadiums and other large areas. They come in two basic flavors:
METAL HALIDE: or MH lamps emit a white light that looks slightly bluish. They are used to light stadiums, convention centers, gymnasiums, and other large areas
where a natural looking light is desired.
HIGH PRESSURE SODIUM: or HPS lamps emit a pink or amber light. They are used for lighting parking lots and other areas where the color of the light is not important. HPS units are much more efficient than MH ones, producing more light and less energy consumed. They are often used alone with no detrimental effect on the plants, and will promote faster plant growth than MH lamps during both vegetative growth and flowering. Combinations of bulbs are _NOT_ required, as the HPS lamp does produce all of the light spectrums necessary for healthy growth. There is a relatively new type of HPS lamp that has become available. It is called the...
Son Agro lamp
Basically the designers of this lamp took a 400w HPS lamp, and added another 30W element to it, However, this new element puts out blue light, to help fill in the parts of the spectrum that a standard HPS is missing. We use SON-T Plus or Agro for years now. And the Bulbs are highly efficient and can be used for 6 crops. I think they're really terrific!
What sizes are for you to use?
MH lamps are available in 175, 200, 400 and 1000 watt sizes. HPS lamps come in 50, 75, 150, 400, 600 and 1000 watt sizes. It works with a 400w HPS ballast. Each lamp requires its own ballast, which comes with the fixtures that are designed to use these lamps, and are also available separately. The Son-Agro (and similar bulbs) can now be found in 170w, 270w, 430w, & 1000w].
The following chart shows how much light each lamp emits, and the area that it covers adequately.
Lamp # of Lumens Sq. Ft
Gardens should receive 1000-3000 lumens per square foot. Successful gardens usually are lit at around 2,000 lumens per square foot. During the vegetative stage, plants stretch out when they receive low levels of light. During flowering the flowers are looser and sparse.
So what is the best lamp for growing?
It depends on your budget. HPS lamps are by far the best overall, but they are also the most costly to purchase and setup. I've also add some pics about High Pressure Sodium bulb suited for SGR 200 Ballast. The colour spectrum is highest in the yellow, orange and red end, which makes the SON-T PLUS especially suitable for flowering 55,000 lume which comes together with the PHILIPS SGR 200 - SON-T PLUS 400 watt High Pressure Sodium Ballast. Optimum illumination for a 60 cm x 180 cm area. Including SON-T PLUS bulb