Answer: Elaeocarpus decipiens, the Japanese Blueberry Tree, is hardy only to about 40F. If yours have wintered over in Everett, it's because they are in a protected area. They grow best in full sun, with moderate amounts of water. I think that moving them out of the protected area may be risky, but it may encourage additional growth. If you're happy with where they are planted, and you know they will survive winter weather, you may want to put up with slow growth as opposed to dead plants.
Best wishes with your landscape!
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