Sorry to have to ask but I'm not familiar with that one. I've only seen the numbers. Is this from a more detailed chart or something? Am I figuring my zone wrong? LOL
Hey MIchelle. Some charts do have the zones broken down by a and b. Wish I could direct you to one but can't think of any off hand.
Go to the american horticultural society's website and look for their zone map..this is the proposed "new" zone map ( updated from the 1990). Southport is a zone 8 and a warm one at that. You are in the northernmost subtropical area in the US..SOuthport and Bald head Island are the northenrmost place for arboresent palms to be native in the US.