Allium caeruleum
Common Name: ornamental onion
Type: Bulb
Family: Amaryllidaceae
Native Range: Siberia, Turkestan
Zone: 4 to 8
Height: 1.00 to 2.00 feet
Spread: 0.50 to 1.00 feet
Bloom Time: May to June
Bloom Description: Sky blue
Sun: Full sun
Water: Dry to medium
Maintenance: Low
Suggested Use: Naturalize
Flower: Showy
Leaf: Fragrant
Attracts: Butterflies
Tolerate: Deer, Black Walnut

Culture

Easily grown in rich, sandy to gritty, dry to medium moisture, well-drained loams in full sun. Plants form dense, slowly-spreading clumps over time. They perform best in dry, sunny areas of the garden. Established plantings have good drought tolerance. Plant new bulbs 2-4" deep in fall. Established plants may be divided in fall. Bulbils that may form in the umbel may also be planted in fall. Plants may self-seed in the garden. Deadhead flowers before seed sets to help control any unwanted spread.

Noteworthy Characteristics

Allium caeruleum, commonly called blue globe onion, is a bulbous perennial that typically grows to 12-24" tall. It is native to dry slopes, steppes and plains ranging from the Caspian Sea to southwestern Siberia, central Asia and northwestern China. As suggested by its common name, this ornamental onion is noted for producing dense, many-flowered, globular clusters (umbels to 1" diameter) of small, star-shaped, sky blue flowers. Flowers typically bloom in late spring to early summer atop stiff stems rising to 24" tall. Stem-hugging, linear leaves appear on the lower portions of each flowering stem, but these leaves typically wither prior to flowering. Flowering plants often appear to lack foliage. Flowers have no fragrance. Leaves and bulbs have an oniony aroma when cut or bruised.

Genus name comes from the classical Latin name for garlic.

Specific epithet means dark blue.

Problems

No serious insect or disease problems. Bulb rot may occur in overly moist soils. Plants may colonize over time, but are not considered to be invasive.

Garden Uses

Ornamental onion for rock gardens, beds and borders, cottage gardens and meadows.