If you're anything like me, reading about HID lighting will create more questions than answers. I'm going to explain what it's all about for you as a beginner.
HID stands for high-intensity discharge. It's not important to understand what that fancy name means technically. What's important to know is that HID is the more traditional method of lighting plants in most commercial or professional set ups.
HID lights are what professional growers would use to provide light to their plants. But you can use them too.
There're two key types of HID lamps:
I know -- more acronyms!!! Whenever you read about HID, you will see mention of HPS and MH lights. This is because they are often used together in the same setup. Why? Because HPS supplies different colour light to MH lights, and each one's suited more to a different stage of a plant's life stage.
If you've read any of my other pages on indoor grow lights, you'll know that plants use only certain colours of light and don't use others (they don't use green). So grow lights focus on providing the colours of light that plants use and prevent wasting of energy making green light!
Plants use different colours of light during different stages of their growth:
Because HPS lights produce a yellow light, they are more suited to the flowering stage of a plant's growth. And because MH lights produce a bluish light, they are well suited to the vegetative stage.
The other thing you have to know about HID lamps is that they need something called a ballast! A ballast is an electronic circuit that controls the current that goes to the light bulbs. If you didn't use a ballast, the light wouldn't start and would get damaged.
Finally, whenever you use any grow lights that generate heat, it's a must to use some sort of fan to blow the hot air away from the plants.
The other main types of grow lights are fluorescent and LED. HID lamps are more suited for use as grow lights than fluorescent lights and are more energy efficient. The newer LED lights are very good and have a longer bulb lifespan than fluorescent and HID lamps and are also very energy efficient.
Not every gardening shop will have HID lighting supplies. You may need to call around or go to a store that's more geared towards professional growers, hydroponics and greenhouses. And of course, there's always the Internet.