Allium cepa, Onion
Amaryllidaceae family
Sunlight: full sun.
Soil conditions: Well-drained, fertile soil.
Can be planted from seeds, sets, and transplants. Onion bulbing is triggered by day length.
Short Day varieties form bulbs when day length reaches 10 hours. Can be grown in the North. Intermediate Day varieties form bulbs when day length reaches 12-13 hours. Can be grown in most areas except far North, and Deep South. Long Day varieties form bulbs when day length reaches 14 hours. Grow best in northern areas including Delaware.

Successful cultivars

Big Daddy (110 days) Spanish style, yellow onion. Long Day. Good storage onion.
Walla Walla (80-90 days) Big round onions, sweet, mild, juicy flesh. Long Day.
Red Candy (95 days) Glossy red, sweet, mild flavor. Intermediate Day.

Common pests & diseases

Onion Maggot
Leafminers
Thrips
Downy Mildew
Leaf Blight
Onion Rust

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This publication was created by Master Gardeners Rick Judd and Gail Hermenau. Photos courtesy of Gail Hermenau.

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