It may sound a little bit funny, but your free marijuana seeds and their buddies that you paid for need a very clean grow area to thrive in. Yes, I know, that sounds so silly when talking about growing a plant (soil anyone) but I am not talking about the medium you choose to grow them in, nor am I talking about their nutrients. I am talking about cleaning and sterilizing the area that you grow in prior to plopping your cannabis plants into the grow room.
The tiniest fungus or mold can hurt your free weed seeds in the long run
Marijuana is pretty resilient stuff, but it cannot fight off everything. Taking the steps to make sure that your grow area is completely clean first is just wise. If you had a marijuana grow in the same grow room that developed mold, carefully clean all the surfaces (floor, walls, lamp fixtures, cords, ballasts, EVERYTHING! ) of the grow area with a light bleach and water mixture in order to kill any spores that might be lying residual or dormant. Wait about three days, and then do it again. The process of slightly bleaching and then waiting for the surfaces to dry out completely is an incredibly effective method for killing germs, spores, and whatever other biotic nasties might be lurking in the cannabis grow area. Sterilize all utensils that were used in the previous grow, or that you might be using for this grow. Metal and ceramic utensils can be boiled; plastics can be scrubbed with a mild bleach solution. Remember that anything you use a bleach solution on needs to be thoroughly rinsed before being used again.
Your marijuana plants and pests
Germs, molds and fungus are not the only things one has to contend with in a grow. If you think that you are creating a perfect atmosphere for your plants to grow in, believe me, you are. You are actually creating a paradise for your marijuana babies, and paradise attracts a lot of undesirable characters. Of course it would, everyone wants to live in perfect conditions. Keeping things clean and tidy helps keep the spider mites and white fly at bay, along with all of the rest of the creepy-crawlies. A clean floor and sterilized surfaces do not attract as many critters as dirty and un-sterile ones do. Observation is a big one in keeping the bugs at bay; know what to look for, and what to do when you see it.