Maybe you could try asking this on the Citrus forum...?

I have a potted blood orange. It is the Moro variety. There are several different varieties but Moro is the most common. I don't get the color on them that I did when I lived in Arizona. There you get that dark blood red but here it is a bit lighter but you still get the nice berry undertones in the flavor. If your tree is potted obviously you are going to have less fruit than one that is in the ground and gets huge! The one in AZ was a monster in the ground. I think they might freeze here which is why mine is potted. My current one is on dwarf root stock and still wants to get big in the pot lol. They state the zone is 9-10 on these. I would trust them in a 9b not sure about here. Most winters they would be okay but when we hit those teens on occasion they would need protection and of course protect them the first few years. Its the cooler night temps that bring out the redder tones. So in N FL if the nights are cooler when the fruit is ripening they get better color.

Blood oranges grow fine but the don't get as dark in colar.I have found a solution it is a soil additive call azomite

Sultry do you take it out of its pot, root prune it, top it, replace with fresh soil etc every few years? How often? I'm asking because 20 gallon container is as big as I can go.

20 gal should be fine. Mine is in a 15 gal. I do pull it out every few yrs and prune and repot. Like I said, you wont get a massive amt of fruit like you would if it was in the ground but it does ok.