Maybe some shorter ones around the edges, but I wouldn't put any tall ones into the mix in random places. Let me rephrase that: I would and I do, but I wouldn't if I were striving for a serene landscape. If you want the rose bed to be restful to the eye, it shouldn't have any radical departures from pattern. If you want the bed to be more exciting than serene, on the other hand, then you shouldn't follow any design rules at all.
