Answer: Your zip codes places you in USDA winter hardiness zone 4, yes. Unfortunately, even with a sheltered microclimate it is unlikely that plants rated hardy to zone 5 would survive your winters and even less likely that plants rated hardy to zone 6 would survive. Weeping cherries and Japanese maples would not be good choices for zone 4 due to winter hardiness issues. I'm sorry I can't be more encouraging.
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