Perennial of the Month-- January 2010 

(cen-tar' ee-ah) (pronunciation at link, turn up volume if too low)

Common name: Amethyst in Snow mountain bluet, cornflower

Family: Asteraceae, aster/daisy

Height x width: 1-2ft high and wide

Growth rate, habit: moderate; spreading, not too aggressively by rhizomes underground especially in cooler climates, upright stems

Foliage: broadly lance-shaped (lanceolate) to 7" long, entire or lower leaves sometimes dentate or lobed, silvery green; stems winged

Flowers: short central deep bluish-purple disc flowers; outer silky white longer ray flowers tubular and fringed at tips into 3 to 5 segments; overlapping bracts beneath the petals; flowers 2in. or more across; late spring to early summer 

Hardiness: USDA hardiness zones 3-8, AHS heat zones 9 to 1; performs better in north than south

Soil: average, well drained, best in alkaline soils; drought tolerant once established; spreads more in moist, organic; avoid wet and soggy

Light: full sun to part shade

Pests and problems: may dieback seriously from stem rot in wet summers, mildew possible under high moisture; sometimes rust, aster yellows

Landscape habit, uses: fronts to middle of beds and borders, massed (best effect) or as specimen, rock gardens, cut flower; combines well with Silver Mound artemisia, blue fescue, oat grass, snow-in-summer, Moonbeam coreopsis 

Other interest: novel flower color for genus; genus named after Greek centaur or healing; used by Chiton the Centaur in Greek mythology to heal his wounded foot; species is native to the mountains of Europe; attract butterflies; may naturalize in gardens and beyond; deer resistant; selected in May 2002 in Netherlands by Elizabeth Sahin from a population of the species 

Other culture: removing spent flowers ("deadheading") may encourage repeat bloom and prevents self-sowing; divide after 2nd or 3rd year to control spread if desired; low fertility may help prevent rampant spreading; may get leggy and floppy if too much shade

Propagation: cuttings, division (can be done in early fall); commercially by licensed propagators, PP18284

Sources:  many specialty perennial nurseries and online