From our friends at HowToGrowMarijuana.com:
Planning your Marijuana Grow Room
You will need to think about the following equipment to get a grow room up and going.
· Reservoir tank and water;
· Grow systems;
· Final plant size – how big do you want these ladies to be?
· Lighting, type and distance between the lights and the plants;
· Power outlets, timers, and meters (temperature, EC and pH);
· Space to work around the growth.
Spend some time planning your marijuana grow room in advance. A well planned grow room will be easier to work in and leaves less room for costly mistakes and accidents. Any space that can be made into an enclosed, lightproof environment will be suitable; from a whole garage, attic, cellar or bedroom down to a cupboard or even a tented off area of another room will do. Unless you are organizing quite a large grow a lot of people buy an entire kit, all-in-one grow box or grow tent. But remember that you will need ventilation and space around the plants to tend to them especially if you are using HID lights instead of LED grow lights.
Ideally, you should have at least 6ft (1.83cm) of height if not more like 10 or 12 feet and easy access to power sockets, water and exhaust. You can grow in smaller spaces but you will need to train your plants downwards on wires on a daily basis as they grow quickly under lights. You will also have to monitor the humidity, heat and air flow of smaller areas more intensively.
Think about discretion. Fans, bright grow lights and pumps can sometimes attract unwanted attention and so should be kept away from neighbors or living accommodation where they may prove a nuisance. It is also important to think about odors. You’re burgeoning crop may begin to smell quite strongly, even from outside your house or flat. More information on eliminating odors can be found here.
Safety is a crucial consideration when planning the growing environment. Electricity and water don’t mix. Keep all electric appliances away from water and up off the floor in case of flooding. Before starting to grow, double check all timers, pipes, leads and electrical connections. It is usually a good idea to buy new gear but well inspected used gear can save you a lot of money. We would always buy new lights though as the bulbs do have a longer life expectancy and old lights can offer poor results.
Give the whole system a dummy run first to be sure that there have been no errors in setting up. Watch that reservoir systems do not overfill on to the floor, an easy way to stop that is with an overflow set up and that light does not escape the room and that the temperature does not fluctuate in the air or the reservoir. If you are using the high energy (high heat output) HPS and MH lights then certainly make sure you keep a fire extinguisher to hand in the grow room. I am not joking.