RickMartin
Omono
Is 76 degrees to hot for soil temp.Rick,
JBP are a better fit for your climate than Mugo. If these JBP die, it's not because of your climate, it's because you got bare tooted trees too late in the season. Don't blame the species for that.
Truely, if you are somewhat of a beginner with pines, I would suggest starting with something a little more established. George Muranaka sell ground grown JBP that have decent trunks, and low branches for about $100. These you would find much more satisfying to work on. The small seedlings you bought need a decade of growing.
Thanks
Rick