This is a cross between
× H. 'Tokudama' which was
Lillian Cannon of Illinois in 1978. It forms a medium size (18
inches high) mound with very pale lavender flowers from late June into July.
The Hostapedia by Mark Zilis (2009), this cultivar "...acts like a white-edged
H. montana....I fully expected it to become
widely grown and very popular. It has not...I cannot ever recall
seeing a well-formed, "pretty" clump of 'Summer Snow'. Most of
the time, the mound has been one-sided or irregular."