Does anyone know if moro blood orange is a late flowering variety? Mine is 4 years old, 7 feet tall, vigorous but does not flower! Satsuma, fig and ruby orange in the vicinity fruit very well. It's fertilized adequately (as are the surrounding fruit trees, and gets ample sun. Is patience required here? 'Cause I'm running out of it!

Is the tree a mature grafted tree, or was the tree started from planting a seed? - Millet

Its a grafted tree. on trifoliate root stock, I believe.

First, I am notr sure what the problem is. There are two things you can do that encourages a citrus tree to bear flowers. (1) Starting in November stress the tree by withholding the amount of water applied to the tree. (2) A couple months before the expected bloom date apply a dilute floral spray of low biuret urea or potassium nitrate to the foliage of the tree. - Millet

If the scion was taken from an immature tree it is almost like starting from a seed.

Well, this year looks like it's toast then. I will try your suggestions for next year. It may surprise me yet as the satsumas have only just started to flower. Perhaps it will flower in the next cople of weeks. i remember seeing somewhere the moro took a long time to get to the business of setting fruit.
Thanks for your help.

I have sprayed potassium on all my tropicals and sub-tropicals as a frost protecting device in the past but did not have to this year. I'll keep that in mind.