The three hardier species are native to cold-winter regions of Europe and Asia and need some winter chill. Gardeners in cold-winter climates know them as harbingers of spring; the earliest ones come into flower with winter aconite (Eranthis) and snowdrop (Galanthus). Less hardy to cold is Peruvian scilla (S. peruviana); despite its name, it is native to the Mediterranean region. All squills have bell-shaped or starlike flowers borne on leafless stems that rise from clumps of strap- shaped leaves.
Cold-hardy species look best when naturalized; grow them in small patches or larger drifts. S. peruviana is most attractive in clumps along pathways, at edges of mixed plantings, in pots. Deer seem to avoid all species.
S. bifolia. Each 8-in. stem carries three to eight star-shaped, inch-wide flowers in turquoise-blue. White, pale purplish pink, and violet-blue selections are available. Each bulb produces only two leaves.
S. peruviana. PERUVIAN SCILLA. Zones LS, CS; USDA 8-9. Grows best with protection from frost. Large bulb produces numerous floppy leaves which appear in autumn and last through winter. In late spring, 10- to 12-in. stems appear, each topped with dome-shaped cluster of 50 or more starlike flowers. Most forms have bluish purple blooms, but there is a white form.
S. siberica. SIBERIAN SQUILL. Does best in Upper and Middle South. Each 3- to 6-in. stem bears several flowers shaped like flaring bells. Typical color is intense medium blue, but there are selections in white and light to dark shades of violet-blue, often with darker stripes. 'Spring Beauty' has brilliant violet-blue blooms that are larger than those of the species.
Plant all types in fall, in well-drained, organically enriched soil. Set bulbs of cold-hardy species 23 in. deep, 4 in. apart; set those of S. peruviana 34 in. deep, 6 in. apart. Reduce watering when foliage yellows after bloom. Hardy kinds will tolerate less moisture during summer dormancy, but don't let soil dry out completely. S. peruviana will accept summer moisture but doesn't need any. Divide clumps (during dormancy) when vigor and bloom quality decline.