Not with this variety, but I have had that happen with others. If the Blue Boy isn't receiving at least 4 hours of full sun, then you should move it. Once I did that, the phlox bloomed. You may not need to move it far. I moved my plant about 10 feet across the garden where the sun reached it sooner and that did the trick.

Nancy, thanks for your response. This phlox IS receiving lots of sun each day and it is right next to other phlox, like David, that are blooming their heads off. And this is the 3rd year in a row this has happened. Methinks this is beginning to look like a candidate for the compost heap.

I planted two Blue Boy phlox in the fall of '07 on the east side of the house, where they get over 5 hours of direct sun. One died last year. The other only gets 3-4" tall and no flowers. Everything else around it is thriving.