Since it is the peak of the summer season, and this is the time a year where we bonsai practitioners deal with hot conditions the most, I thought it would be interesting and perhaps helpful to discuss trees which have been found to be, to varying degrees, heat intolorant when grown in pots. The best example I have to start out this discussion is Fraser fir (Abies fraseri). This one, I have found is extremely heat intolorant, moreso than many boreal species of conifer. About 8 years ago, while living in Fl, I purchased about 10 different species of conifer, such as Norway Spruce, Black Hills Spruce, Alberta Spruce, Oriental Spruce and a few species of fir, including Fraser fir. All of these were 1-3 feet in height saplings. All survived through the summer there, kept mostly shaded during the afternoon and evening, except the Fraser fir, which was dead within 3 weeks of arrival. The tree arrived in mid-April and was dead by early May. Now that I am in PA, I have been gradually building up my collection of pre-pre-bonsai saplings to work on as bonsai in the long term. I received 3 young Fraser fir in the mail a couple days ago (all just over a foot in height and pot bound in small 2-3 inch black pots. The two in shade are fine as of this afternoon, but the one in I sat in direct sun is completely dead, even though the roots are as moist as when it arrived. Temperatures both yesterday and today peaked in the low 80s. I conclude that for bonsai purposes (grown in a pot), Fraser fir is difficult at best in locations that ever experience hot weather, because the roots cannot get really warm/hot even for short periods. What other trees have you all found to be intolerant of periods of warm or hot weather (either struggles or just flat out dies).