anything that is sitting in the sun most of the day, I would say 70's and up. That's how bricks and cob houses were made. I do use straw and occasional lime in my clay soil, but the lime doesn't go in until the straw has decomposed enough to build up a nice, several inches deep loam that...
My preference for my run (10x20 ft) is straw. I'm in northern Pennsylvania and have clay soil. There are muddy conditions in the late fall and all spring long - rarely in the summer, but not unheard of. We generally have frozen ground all winter, and, more often than not, snow cover.
During...
I would avoid sand in run that is exposed to the elements. It makes a mess of your chickens' feet if it freezes. Also, if you have a clay soil and you mix in sand and lime (chicken poo)....and then it bakes in the sun on a hot day....
I like the deep litter method for my run. I do use coarse...