I may be wrong, but I think it's roughly the Mason-Dixon line that is the boundary. It all depends on elevation and micro-climate too.

With regards to my "6 inches of ice" comment, it takes a prolonged cold spell for 6" of ice to form. If there is no snow, a week of temps in the single digits "F" will do it, or a much longer period of time below freezing but between 20°F and 32°F. They will survive and grow perfectly well in your climate, even with some ice forming on the pond.

Have you ever seen ice thick enough there for people to walk on?

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3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).