I read through his thread and he overwinter his potted mumes in his garage and his pre-prebonsai mumes were grown in the ground. The mumes I had (The ones growing on their own roots) were in pond baskets that sat on the ground during the winter. I’d guess the ground provided the necessary protection for the roots to survive. I’m not saying it’s definite proof that mumes on their own roots have difficulty surviving winters here but it does lead me to believe that it is a strong possibility.
Since I don’t wanna place my mume in the ground without having examine the roots, this winter I’ll overwinter mine in the garage and see what happens (hopefully I have good news

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I also was thinking maybe I’ll bury the pot the mume is in, in the ground sometime in September so that the roots have enough time to escape into the ground. Idk if I wanna risk it. But I’ll update the thread if I do end up doing that.
Thanks for bringing that to my attention though. This may have helped me figure out how to solve my mume problem.