Welcome to the forum Julia.
The b/w rose looks the only good shoot among all. Actually it is more than good, very very good.
The other 3 have composition issues. I remember we had few very good photographers shooting flowers here on the forum. Look up their work.
Yes...B&W is the best,,,violet would have been lovely if the flowers were fully within the frame...the remaining two are compositional problems as already been pointed out'
O, forgot...Hearty Welcome