I am relatively new to growing sphagnum moss and have several cultures going right now. I have been leaving several trays of it outside in the elements where it freezes solid for an extended time, keep a few in my unheated pop-tent greenhouse with my overwintering Sarracenia and Dionaea, and even have a few in my unheated garage. I have lost none of it yet, and some even appears to be still growing, albeit quite slowly.
My question then: would you think the moss would grow more in the unheated garage under lights or outside where it sees the stronger sun but sees colder temperatures and extended freezing? I am just trying to optimize my cultures I guess.