Cool blue flowers top these upright Asian native shrubs from midsummer to frost. Generally grown as woody-based perennialsif plants don't freeze back in winter, cut them nearly to ground before spring growth flush to ensure a good base for the new season's growth. Bear dense, stalked clusters of small flowers on current season's growth; trim after each wave of bloom to encourage repeat flowering. Provide good drainage, since plants can rot in wet soil. Not browsed by deer.
C. x clandonensis. BLUE MIST. Low-growing mound (to 2 ft. tall and wide) of narrow, 3-in.-long, gray-green leaves. Clusters of small flowers top upper parts of stems. The original selection, 'Arthur Simmonds', is still the hardiest and most reliable; it has bright blue blossoms and gray-green leaves with silvery undersides. 'Heavenly Blue' and 'Sapphire Surf' bear deep blue blossoms; 'Dark Knight', 'Longwood Blue', and 'Sterling Silver' also with deep blue blooms, have silvery foliage. 'Worcester Gold' has yellow leaves and lavender-blue flowers. Leaves of 'Summer Sorbet' are green with yellow edges. 'First Choice' is compact, with profuse dark purple blossoms; it blooms over a longer period than other selections.
C. incana. COMMON BLUEBEARD, BLUE SPIREA. Taller than C. x clandonensis, with looser, more open growth to 34 ft. tall, 5 ft. wide. Lavender-blue flowers appear in leaf joints. 'Jason' has golden foliage. 'Blue Myth' is noted for deep blue flowers and compact form, growing just 2-3 ft. tall and wide.