Answer: Oleanders (Nerium) are not at all cold tolerant and are damaged by frosts, so they are considered reliably winter hardy only in frost free areas. A few specialyl hardy varieties may be hardy into zone 8 -- but in general think Florida or southern California. They would not be expected to survive your winter weather outdoors. Unfortunately, I suspect they are dead. (Your zip code places you in winter hardiness zone 6.) I'm sorry!
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