The blooms of Louise Marx are quite large, easily measuring 6 inches. In his book "Peonies" Allan Rogers notes that this cultivar is one of those recommended for commercial cut flower production.
Just 5 years old in this picture, this is a strong grower to a mature size of 46"-48", with blooms averaging 6 inches in diameter. Stunning when covered with blooms, and because there are several side buds per stem, it stays in bloom for weeks! A late blooming Japanese variety. The Caprice catalogue states that there is a "rich fragrance" but not to my nose, alas.