I second the opinion that flowers should 'mostly' be shot in colour - and usually the more vivid, the better. However, that is not to say that is the cast in stone rule. The first picture to me has no clear focus / attraction point. The (relatively) deep depth of field also creates a lot of clutter, preventing the eye from being led through the image.
Black & White photography, in my opinion, is all about contrasts - highlights and shadows. Your second image does this to much better effect with the only real criticisms are a replica of the previous comments - angle : buildings somehow look better from above and the heads in the shot perhaps unbalance the overall composition.