Make sure your icing isn't too thick. Try thinning it with a little corn syrup. That helps the petal edges be smoother.
CakeMommy3 is correct that your frosting is to thick. Thin it out and you won't have that problem any more.
Could also be that your icing is "airy". Air bubbles can cause the same issue. I try to make my icing the day before, refridgerate overnite, then take out, let warm on counter, remix. This seems to help.
Also, don't mix buttercream fast, mix slow and just let it go longer in mixer, you don't want to add any air.
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