Providing your plants with the right light is one of the most important things you can do for them.
There are a large variety of lighting systems that offer different benefits.
Light Emitting Diode (LED):
Growers looking to find a more energy efficient lighting system have been increasingly using LED grow lights.
LED lighting systems can be fairly expensive, but the technology is relatively new and is rapidly developing so hopefully that will eventually bring the price down. LEDs run hotter than HID lights and therefore need to be placed farther away from your plants.
When it comes to energy efficiency LED and HID are said to be equal. That might sound great, why would you pay or expensive utility bills with HID lights when LEDs are just as efficient? It's a bit misleading. While they are equally efficient when it comes to energy use, the yields with LED lights are lower. Another disadvantage to LED lighting systems is that it can cause leaf discoloration to your plants, but that doesn't seem to effect the development of the bud. LEDs are also more expensive upfront than HID lighting systems.
However, many growers will tell you that the quality of the cannabis is improved with LEDs. The smell is thought to be better along with the trichome development.
There also is a lot of different options available when it comes to LEDs. There are varying sizes, shapes, and strengths of lights. You can turn almost any space into a grow room with an LED.
Compact Florescent Lights (CFL):
Despite being designed and marketed for in home lighting, CFLs are quickly becoming a popular lighting system for small garden growers and growers on a budget. They are not great for large grow rooms.
You can place the lights very close to the plants without burning them because CFLs produce the least amount of heat of any lighting option.
It is also ridiculously easy to make your own lighting hood, and CFLs are the easiest to adapt to suit your grow room.
They also come in many different color options allowing you to experiment more with light spectrums. You will need to adjust the lights daily if you want to receive your maximum yield though which is time consuming.
You will need to do some research when choosing bulbs. It can be confusing because most are not marketed towards indoor cultivation. 23 watt CFL bulbs seem to be the most efficient for indoor growing but still are not as efficient as HID. The higher you go with wattage though the less efficient you become and at higher wattages CFLs are significantly less efficient than HIDs.
High-Intensity Discharge (HID):
HID lights offer incredibly powerful light and have been known as the "Gold Standard" in indoor lighting systems for a long time.
They come in two varieties, High Pressure Sodium (HPS) or Metal Halide (MH). MH lights give off an intense bluish white light that encourages vigorous vegetative growth. HPS lights provide yellow-orange spectrum light that promotes flowering. Both HPS and MH stimulate the plants to grow quickly and produce high yields. Lights may vary from different manufacturers.
HID lights are the most efficient light source in terms of electricity use to light output if you can get past the high utility bills. They light up the room so efficiently it's like having the sun inside. HID lights are the best option for those growers looking to set up a large grow room or who want to eventually scale up to a larger operation. HID is the perfect option as long as you can afford the equipment and maintenance costs. You will also need to have way to cool the room down due to the lights running hot.