SET UP II reflection and air flow

Once you have the space chosen you need to do and think about a few things before you put the plants in there.
1st Clean --  I know this is not going to be the most fun part of growing but it is important and can help reduce countless problems later. This is going to be the home of your plants so clean out all dust, debris, and wipe down every surface (walls ceiling and floor) with warm soapy water. If you have had pests or disease use 5-10% bleach or hydrogen peroxide or isopropanol. Plants give off moisture so if you think you can continue to use your closet as both a closet and a grow area you better think about how humidity will affect the things other than plants you keep in the closet. (See ventilation below)
Reflective surfaces – The amount of light that hits the plants will increase growth and you can greatly increase the light getting to the plants by having reflective surfaces. This is extremely important with HID compared with the more linear light put out by LED”s and fluorescent lights. Some good reflective materials are mylar,  flat white paint, aluminum foil, cardboard or plywood painted white, or even white cloth. You should try to cover all areas so that all the light gets reflected around until it is absorbed by the plants. Everyone thinks to cover the walls, but the floors and the ceiling should be made as reflective as possible too. Light can travel 186,000 miles per second so it can bounce around on many things in your closet. If you think you don’t have any reflective material I bet you have aluminum foil in your house right now (Even if you don’t have it you can get it with a few coins at the grocery store so go get some and notice the difference). Good growers use wide heavy duty aluminum foil in areas that won’t be disturbed and use cloth or plastic curtains where you will have to move the reflective material to get to the plants. It is easier to hang foil vertically (up and down) than horizontally (left to right).
Ventilation Most people think to ventilate to remove humidity and heat but most importantly you should do it to provide your plants a fresh source of CO2. I have grown plants in a closet without true ventilation. I would open the door each day to refresh the air and I had a small fan in the closet (It was 3x4 roughly). That is all it takes is light air movement and occasional refreshing of air to grow plants bigger and better.

One thing I like to use for ventilation is a carbon filter. You can run one in your grow room and direct the airflow over your plants at the bulb to increase airflow and reduce heat around the plants. The added benefit is the carbon filter cleans the air of many fungal spores and other diseases.

Good Growing,
Dr. E. R. Myers