I'm starting a new perennial bed that has two Burkwoodii Virburnum shrubs in it. I would like to add three peonies in a row just to the right one of the Virburnums. I understand that peonies don't like to be crowded and I have 13 feet for three. They are listed as medium tall.

The shrubs are now 7 years old and have grown to their reference book height of 8 to 10 in height. They are also as wide as the book says. I'm hoping they won't grow any bigger or they might infringe on one of the peonies. What do you think? Is the 13 feet width enough?