I'm wondering what kind of bulb I should use to grow a single cannabis plant in an enclosed location(closet). there is enough openings in the closet to give the plant ventilation and i intend to move it outside during night so that it has sufficient co2. i want the cheapest bulb, but it should still be effective. i'm not interested in spending a lot of money to grow a single plant one time - this is a project, not a harvest by any means. so please, i've looked everywhere and haven't been able to find anything helpful. i know there are different kinds of lights such as metal halide and low pressure sodium, etc. but what are the required lumens and kelvin for cannabis to grow?
if you are looking for cheap stay away from the HPS/MH normally they are not cheap. but this should answer the rest of your questions on lumen and kelvin http://forum.grasscity.com/absolute-beginners/122824-kamels-cfl-guide.html
If you want to use a HID (High Pressure Sodium, Metal Hallide)..you will get lots of great light, but it will cost a bit more. To run these bulbs, you need a ballst and reflector. They also use more energy, and emit a decent amount of heat. If you want MAX yield, these are the way to go. If you're less concerned with yield, and just want to grow a plant, then get some compact flourecense bulbs, or regular flourecense bulbs. These bulbs will provide less intensity and yield, but they are much cheaper, cooler, and less hassle. If you decide to use a HID, you'll probably want a Metal Hallide for vegetation, and HPS for flowering stage. Don't be overly concernced with Kelvin ratings at this point. Make some more general decisions about what direction you want to go. Good luck.