Hey, welcome to my (Quick Fire) world. :-) I've had the same experience as you with my six. I swear that if you prune them in the current year, they don't bloom, and/or don't bloom as much.

None of mine is in full sun, but like with your experience, the flower pattern doesn't seem to be sun related. I didn't prune any of them this year, and even the ones in a lot of sun have strange bloom patterns, as in half the shrub will have blooms on most branches, and half the shrub has only sporadic blooms. Blooms do seem to be on older growth though...so even where it was pruned LAST spring, it seems to have far fewer blooms.

I'd personally only put this shrub in full sun and where it could go unpruned. But I know some people rave about this hydrangea and it does well for them.

Thanks for the reply :)
I just walked around the yard and really looked to see which I had cut and which I didn't. Turns out I cut back 2 of the 10. One is a Quickfire tree form in 100% full sun but it is COVERED w/blooms. The only other QF I cut back was this one that isn't blooming. The 2 blooms that are there are on stems that weren't cut. I'm thinking that this might be the reason although I can't figure out why the tree form has blooms bc I cut that one back severe also.
As far as sun goes, my yard is mostly shade. I panted most of these Quickfires in dappled shade with maybe a couple hours of direct sun at best. I had read that it was a bad idea but to be honest they are all blooming very well. The only plant not blooming is in one of my sunniest spots.
I'm thinking that its the cutting back. Thanks for pointing me in that direction. Next year I'm going to experiment a little bit and cut back one of the good bloomers from this year. Over all it's a great shrub. I think it might be luck of the draw with getting a dud or not. I bought them from several different nurseries. Maybe some growers have better stock than others?
By the way? Do you have deer? Maybe the shrubs with blooms on one side had been pruned by deer? It would explain the lopsided blooms.

I have deer, but I spray regularly, and these haven't been deer-pruned...I can tell by the growth.

I've also wondered about the stock.

I have three "out back" where I can leave them, so I've done no pruning this year and will do none next and see what happens.

For part shade, I haven't found a paniculata that beats Limelight. I tried Quick Fire because I wanted something earlier.

Quickfire hydrangea like all paniculatas bloom on the current years growth.....you can cut them back (early spring) or not cut them back and they all will produce blooms on this year's growth......but with that said, nature is not exact science, nor will each shrub perform at 100%...a number of factors can include soil conditions site location (Sunlight) and the vigorousness of individual plants......some may take a season or two before they become established enough to perform at their optimum.

It is hard trying to tell when it is safe to prune with these guys because the flower buds are initially invisible. I prefer to prune way early, as in way before they leaf out. Which is February here in the South.

Did you prune the QFs before they leafed out or after they leafed out? Just wondering...

I didn't prune mine this year, only last. I've had them for 4 or 5 years.

Most folks have thus far recommended pruning QF in late Fall after the leaves have fallen... Otherwise, just cut the spent blooms off and prune no further. Doing that this past season has resulted in at least 100 flowers on a 5x4' shrub this time around!

This said, QF so far has been the best in my yard at "building it's own structure" without much general pruning. Much like a healthy rose bush, it has sent large new branches out to fill in "voids" in the middle that weren't yet occupied. Ironically the "carpet" rose next door has been encroaching on the QF, and I thought it was going to be the other way 'round...