This is a seedling of (a seedling
H. rupifraga x H. 'Maruba Iwa') x H. 'Blue
Jay'. It was registered by
Shady Oaks Nursery of Minnesota in 2005 and received a U.S. patent in
2006. It forms a slow
growing mound about 14 inches high by 36 inches wide and bears pale
lavender flowers from late July into August. The leaves are
slightly cupped and corrugated with thick bloom on the
The New Encyclopedia of Hostas by
Grenfell (2009) states: "Best in the shade where lower light levels help
retain the bluest leaf color, but not under trees where raindrops and falling
debris might spoil the appearance of the leaves. Moderately vigorous."
Mikiko Lockwood in an article on The Hosta Library titled,
A Little About Japanese Hosta Terms defines the term iwa as rock, Iwa Gibōshi or
H. longipes and the term maruba as round leaf or round-leafed.
United States Patent: PP17309 (2006)
Abstract: A new cultivar of Hosta named ‘Prairie
Sky’, that is characterized by its intensely blue
foliage with leaves that are heart-shaped, slightly
cupped and lightly puckered. ‘Prairie Sky’ has a
vigorous growth habit and blooms in mid July to mid
August with pale lavender flowers on erect scapes.