Answer: Based on your zip code, you are actually in zone 6A -- the coldest part of zone 6. So I would suggest you follow your local nursery's advice based on their local knowledge and experience with how these plants perform in your area. It is better if possible to keep them cool (45 or lower) but above freezing so the soil does not freeze solid. If you think your storage area is only occasionally colder than that, perhaps you can insulate the roots a bit more by heaping mulch around the pots (do not cover the crown of the plant) or double potting them. Good luck with your agapanthus.
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