I am sorry for this delayed reply to your gardening question. The spring rush has brought a deluge of questions and we are working hard to catch up!
It depends on which type of philodendron you planted and where in the landscape they were planted (how protected is the location). That said I would count on having to protect them as in most cases in your zone philodendron is not going to be dependably hardy.
Thanks for the question. Best wishes for a wonderful gardening season. Please stop in again soon!
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