Zones are not as they seem sometimes. I mean if you average 51f...that's zone 12. 51 (11c) for a daytime temp is sweater weather. I guess I would even be happy at a regular z10a if our lowest low was 34f instead of 10b's 35f. Anything that's above the formation of frost works for me. After a a couple of back to back winters where we hit the freezing mark? I even came close to removing the Brugs and the Wigandia..even banana. These are large shrubs in my yard...seeing them at their worst from Dec-Feb is no fun gardening.
I noticed long ago that Ben and Troys climate produces subtropicals that never see a frost..like greenhouse perfect. If I can get five more winters in a row like this one...