High Intensity Discharge lamps (HID) | HID Lighting

metal halide and high pressure sodiumHigh Intensity Discharge lamps are typical in a grow room setting.  These light bulbs can be either high-pressure sodium or metal halide.  The light emitted from a high-pressure sodium lamp is yellow and bright to mimic the fall tint of the mid-day sun.  The high-pressure sodium lamps are used during the flowering stage of the grow cycle.  Depending on the type of plants you are growing, you’ll switch you lamp from the metal halide to the high pressure sodium and change the light cycle down from 18 hours a day to 8-12 hours a day.  You can gradually bring your plants down to 8-12 hours of light each day, there’s nothing wrong with that.

The metal halide lamps are primarily used for the vegetation, or growth cycle.  The metal halide lamp emits a bright white light to mimic the bright white summer sunlight.  During the vegetation stage of the grow cycle, you’ll want to keep the lights on 18-24 hours a day.  It’s a good idea to use a lower power compact flourecent light when you have seedlings.  It’s only when you’re looking for really strong growth will use a metal halide lamp.

High Pressure Sodium Lamp

High Pressure Sodium Lamp

During the vegetation stage, you can safely clone your plants.  Do not try and clone a flowering plant, you will end up throwing away whatever weirdness you just wasted cloning gel on.

To run either the high pressure sodium or metal halide lamps, you’re going to need ballast, and a special socket that the lamp is plugged into.  The plug is powered by the ballast and the ballast plugs into the wall.  However, since you’re probably not going to set your alarm to unplug the ballast every 18 hours, you’ll want to plug your ballast into a timer.

Most lighting kits come with all of the above and hood that reflects light down.  You can check ebay for really cheap prices on full lighting

Metal Halide Lamp

Metal Halide Lamp


Some considerations:
– Mechanical ballasts will run metal halide lamps only.
– Electronic ballasts can run either metal halide or high pressure sodium lamps
– Digital electronic ballasts will run either automatically without needing to change any setting, (just change the HID and you’re done)
– There are hybrid-spectrum lamps that are both metal halide and high pressure sodium.

This is just the beginning, we’ll be getting into more depth about HID lighting and how to best use it in another post.


Digital Electronic Ballast

Digital Electronic Ballast

  • High Pressure Sodium
  • Metal Halide
  • Compact Florescent grow lights
  • Vegetation Light Cycle
  • Flowering Light Cycle
  • Wattage
Thanks for reading.
Stay Green!


  1. […] your plants get each day, you are likely going to control the amount of light your plants get with HID lighting.  So, in a limited space grow room, you’ll need to “veg” your plants in the same […]

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