Roy Klehm of Illinois registered this sport of H. 'Blue Moon' in 1998. It forms a large size (21 inches high) mound of foliage.

This is yet another cultivar that has some confusion in its background. According to The Hostapedia by Mark Zilis (2009), "...'Blue Moon' only achieves dimensions of 10" high by 26" wide after many years of growth, with leaves no bigger than 5" by 4". The number of vein pairs also differs. 'Blue Moon' usually has 10 or 11 (never more than 12), but 'Summer Joy' bears as many as 16 vein pairs. A true white-centered sport of 'Blue Moon' would probably grow no larger than 6" in height with leaves no bigger than 4" by 3" and a vein pair count of 10-12. What then, is the identity of 'Summer Joy'?"