Hi Dotsie,
I did a little (tiny) research and all I could come up with was a study done at a botanical garden in Europe that said two thirds of plants will be effected by unusual weather patterns.
You've got me curious so I'm going to look into this further, when I've got more time. I'll let you know what I find out.
As far as my own past experience, most of mine have come through okay (talking about when I lived in NY) but I can't remember a crazier year for weather than we are having now. I do remember losing some tulips one year though after a late snow storm.
Nothing here in NC seems to be being effected oddly YET. My daffoldils have sprouted but aren't blooming.
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Where I've been lately