Answer: When you are on the edge of two zones, your local microclimate becomes particularly important. A windy location, for example, can push your zone colder where a sheltered location can nudge your zone warmer. To be on the safe side, I would suggest going with plants rated to zone 4 and experimenting with a few rated to zone 5 and see what happens. Your neighbors and possibly your County Extension (866-7920) may also be able to help you pinpoint your expected zone performance more closely.
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