Planting Onions

Onions are a kitchen staple. Grow onions from seed, seedlings, or sets (small dry onion bulbs started the year before). Bulbing onions require 80 to 120 days to reach harvest. Green onions are harvested before they form bulbs, in 40 days or less. Spring onions form small, immature bulbs and are harvested in 40 to 60 days. 

Planting Calendar. Onions require cool weather to start growth and produce green leaves for green or spring onions and warm weather to produce mature bulbs. Onions seeds, seedlings, and sets are frost hardy. ( Learn more about types of onions and varieties, click here. )

● Spring planting. Plant onion seed, seedlings, and sets in early spring in northern and cold-winter regions for harvest the following autumn after they have formed bulbs. Sow seeds directly in the garden as early as four weeks before the average last frost date, or start seed earlier in late winter in a greenhouse or cold frame and transplant seedlings to the garden in early spring.

● Autumn planting. Plant onion sets in late summer or early autumn in southern and warmer regions. Over winter these onions for lifting mid summer or autumn the following year. ( Tips on planting the fall garden, click here.)

Place. Plant bulb onions in full sun. Green onions can be planted in partial shade.