You need more cold weather. You are lucky to get any red in your blood oranges in zone 10!

Mine in Long Beach, CA, were never deep red either. That said, time did help a bit, as in 4-5 years later.

Beyond that, I thought the red was related to which cultivar you have, also high heat as can be had in California's inland valleys.

As Mr. Texas says, in Florida we just never get enough cold weather to make it happen. The best we can hope for is flecks of red on an otherwise orange fruit. But they still taste like blood oranges.

If you want a fruit that turns red (really deep pink) you might try 'Cara Cara' navel, but of course that's a different pigment (lycopene) and it doesn't taste like a blood orange.

Thanks all,
After posting here I Googled it and guess what...there are different types of Blood Oranges. I guess mine is the kind that has less Red but more flavor (Tarocco Vareity). Can't really complain about that...but I will keep an eye on it to make sure that a REAL cold snap does or does not affect it.
Tam

Here is a link that might be useful: Wikipedia Article on Blood Oranges

Tam,
Yes, there are variations, but Tarocco can be deep burgundy purple if grown in a climate like Spain's. In Florida, even the coldest winter never stays cool enough, long enough, to do it. We just have to live with that.

hhmmmm
mine is fine and produces really nice dark pigmented oranges down here in south fl. never gets really cold or cool here either

What variety, Orchidguy?

moro

My moros are orange flecked with red (5%). So it cannot be just the cultivar

The chemical in Moro Blood oranges that causes the dark red blood color is anthocyanin, Anthocyannin is a temperature dependent chemical. It is COLD weather that changes the fruit color to the red blood texture. Therefore, the night time temperatures must be cool to generate the color change. Drop the night temperatures down into the low 50's. Grown to warm the anthocyanin does not turn to the full color.