About 500 species, all from the Northern Hemisphere. Relatives of the edible onion, peerless as cut flowers (fresh or dried), useful in borders; smaller kinds are effective in rock gardens. Plants bear small flowers in clusters (umbels) atop leafless stems that range from 6 in.5 ft. tall or more. Umbels may be tightly or loosely arranged; some look like spheres, others like exploding fireworks. Bloom comes in spring or summer with flowers in white and shades of pink, rose, violet, red, blue, and yellow. Most ornamental alliums are hardy, sun loving, easy to grow; they thrive in deep, rich, sandy loam. Plant bulbs in fall. Lift and divide only after they become crowded.
Leaves of most alliums are narrow and upright, varying in form from grassy to strap shaped; they often begin to die back before flowering starts. Small flowers come in roundish, compact or loose clusters. Some are delightfully fragrant; those with onion odor must be bruised or cut to detect it. All alliums die to the ground after bloom, even in mild climates. Seldom browsed by deer.
A. aflatunense. Zones US, MS, LS; USDA 6-8. Blooms in late spring, bearing tennis ball-size clusters of lilac flowers on stems 2 5 ft. tall. Resembles A. giganteum but with smaller flower clusters. 'Purple Sensation' has violet-purple blooms.
A. atropurpureum. Zones US, MS, LS; USDA 6-8. Stems to 2 ft. tall carry 2-in. clusters of dark purple to nearly black flowers in late spring.
A. caeruleum (A. azureum). BLUE ALLIUM. Zones US, MS, LS; USDA 6-8. Cornflower blue flowers in dense, round, 2-in. clusters on 1- to 1-ft. stems. Late-spring bloom.
A. carinatum pulchellum. Zones US, MS, LS; USDA 6-8. Loose, pendent, 2-in. clusters of reddish purple flowers on 1- to 2-ft. stems. Blooms in summer.
A. cepa. See Onion
A. christophii. STAR OF PERSIA. Zones US, MS, LS; USDA 6-8. Distinctive. Very large clusters (612 in. across) of starlike, lavender to deep lilac flowers with metallic sheen. Late-spring bloom. Stems are 1215 in. tall. Leaves to 1 ft. long, white and hairy beneath. Dried flower cluster looks like an elegant holiday ornament.
A. giganteum. GIANT ALLIUM. Zones US, MS, LS; USDA 6-8. Spectacular softball-size clusters of bright lilac flowers on stems to 35 ft. or taller. Late-spring bloom. Leaves 1 ft. long, 2 in. wide.
A. 'Globemaster'. Zones US, MS; USDA 6-7. Popular selection bearing astonishing clusters like a ball on a stick. Clusters are 68 in. across and deep violet in late spring. Stalks stand 212 ft. tall.
A. karataviense. TURKESTAN ALLIUM. Zones US, MS, LS; USDA 6-8. Dense, round, 2- to 3-in. flower clusters in midspring, in colors from pinkish to beige to reddish lilac. Broad, flat, recurved leaves, 25 in. across.
A. 'Millenium'. Zones US, MS, LS, CS; USDA 6-9. A reliable perennial summer-blooming onion with 10- to 15-in. tall stems topped with golf ball-size pink blooms.
A. moly. GOLDEN GARLIC. Zones US, MS, LS; USDA 6-8. Stems 918 in. tall bear open clusters of flowers in bright, shining yellow. Late-spring bloom.
A. neapolitanum. Zones US, MS, LS, CS; USDA 6-9. Spreading, 2-in. clusters of large, fragrant, white flowers on 1-ft. stems bloom in midspring. Leaves 1 in. wide. 'Grandiflorum' is larger, blooms earlier. A form of 'Grandiflorum' listed as 'Cowanii' is considered superior. Grown commercially as cut flowers.
A. oreophilum (A. ostrowskianum). Zones US, MS, LS, CS; USDA 6-9. Loose, 1-in. clusters of rose-colored flowers on 8- to 12-in. stems in late spring; two or three gray-green leaves. Good for rock gardens, cutting.
A. porrum. See Leek
A. rosenbachianum. Zones US, MS, LS; USDA 6-8. Baseball-size clusters of rosy purple blossoms with contrasting white stamens in late spring.
A. sativum. See Garlic
A. schubertii. Zones MS, LS, CS; USDA 7-9. The mauve starburst of flowers measures 810 in. across, yet remains subtle. Blooming in late spring from 1224 in. tall, it prefers full sun, transitioning to partial shade in warmer areas.
A. scorodoprasum. See Garlic
A. sphaerocephalum. DRUMSTICKS, ROUND-HEADED GARLIC. Zones US, MS, LS, CS; USDA 6-9. Tight, dense, spherical, inch-wide, red-purple flower clusters on 2-ft. stems in early to midsummer. Spreads freely.
A. triquetrum. THREE- CORNERED LEEK. Zones US, MS, LS; USDA 6-8. Heirloom bulb that blooms late spring and early summer when others have finished. A cluster of white bells stand 1418 in. tall. May naturalize in moist soils.