A small indoor space should be found that can be used to germinate seeds; these vegetative starts are placed outside to mature in the spring after last freezes are over. The space can be a closet, a section of a bedroom, a basement area, an attic or unused bathroom. Some people devote entire bedrooms to growing.
The space must be light leak proofed, so that no suspicious light is seen from outside the house. This could invite fuzz or rip-offs.
The space should be vented. Opening the door of a closet can be enough ventilation if the space is not lit by big lights that generate a lot of heat. Separate exhaust and incoming air vents are best. One at the top of the room to exhaust air into the attic or out the roof, and one to bring in air from an outside wall or under-floor crawl space. Use fans from old computer cabinets, available from electronic liquidators for $5 each. Dimmer swithes can be used to regulate the speed/noise of the fans. Use silicon to secure the fans to 4-6” PVC pipe pushed thru a round hole cut in the floor and ceilings. Use lots of silicon to damp the fans vibrations, so that the walls do not resonate to the fans’ ocsilations.
Line the walls with aluminum foil, dull side out to diffuse the light and prevent hot-spots, or paint the walls bright white to reflect light. Aluminized mylar, 1 mil thick is best.($20 for 25 feet of a 4’ wide roll.)
Mirrors are not good to use, since the glass eats light!
Line the floor with plastic in case of water spills, etc. Set up a voltage interrupt socket and be sure the electrical wiring will handle the lamps your going to use. Always place ballasts for HID lamps on a shelf, so they are above floor level, in case of water spills. Spacers place on the floor under a ballast will work too.
A shelf above the main grow area can be used to clone cuttings and germinate seedlings. It will allow you to double the area of your grow space and is an invaluable storage area for plant food, spray bottles and other gardening supplies. This area stays very warm, and no germination warming pad will be needed, so this arrangement saves you $.
Hang a light proof curtain to separate this shelf from the main area when used for flowering. This will allow constant lights on the shelf and dark periods in the main grow area. Velcro can be used to keep the curtain in place and ties can be used to roll it up when tending the garden. Black vinyl with white backing works best.
Now you need light. A couple of shop lights will be fine if you just want to start hemp plants inside and then take them outside to grow in a small greenhouse. They can be purchased with bulbs for about $10 each, or without bulbs for around $8. Try to find them on sale. Use one Cool White and one Warm Light type bulb in each to get the best light spectrum possible for plant growth. Do not use expensive Grow Lux type bulbs, as they do not put out as much light, and therefor do not work as well in most situations (go figure). If Cool White is all you can find, or afford, use them. They work fine, and are by far the cheapest.(About $1-2 each.)