Developed - as opposed to small and newly planted - Japanese flowering cherries are best left alone except for cutting out of root-stock sprouts.

This post was edited by bboy on Mon, Apr 7, 14 at 15:13

I entirely agree with the spirit of what bboy said. It is best left alone and appreciating its natural habit. However, it's a danged shame to be removing this year's blossoms since they developed last year and the trimming will impact the show.

That being said it is likely to do it no physical damage, even if done at this time. I venture to put that forth, as I've done it and quite severely I'm embarrassed to say. I planted one quite inappropriately through my own negligence, thinking it was a totally different cultivar who would remain quite dwarf and have a much smaller spread. The only options were to remove it, or pollard it. I figured if I tried to move it that it would not thrive, and I'd likely end up just removing it, so I decided to pollard it having nothing much to lose. I sacrifice the blooms every few years in the process, and it's a rather formal and unnaturally shaped tree now, but handsome enough I'm willing to invest in the high upkeep involved and it's been there now quite a few years. Your call.