well, I made a cherry blossom cake and it is in my photos. it was only 3 tiers but I did not need 200 cherry blossoms.
i think i maybe made 50 and didn't even use them all.(this also depends on the size you want them small, med, lrg)
I used the 5 petal cutter that comes in the wilton kit to make the roses....then after cutting out very thin fondant I put them into egg cartons to shape them some. after they dried i just used petal and luster dusts for the color. and yes!! i did have to dust the backside of the petals that were showing because you may just see them from all sides. and I dusted from the outside in...I think cherry blossoms have more color on the outside. so you would want to do it that way.
these are VERY easy...you will get addicted to making them!
good luck! pm me if you have any more questions!