It depends on the strain and like it was said once that I know of, invest in a carbon filter. YouTube and a 'mentor' are awesome aids, along with this site which I only discovered today, are a great source for information about the growing process. I grew my first indoor plants in my closet from some purple kush feminized seeds I ordered online and it was the best bud I have ever smoked, if I do say so myself! Also trial and error are valuable learning tools, hopefully you don't experience too many errors with pricey clones or seeds, as that could get expensive. My best advice is to always do your homework, research the hell out of growing weed indoors and seek multiple sources. Good luck to you and happy growing!