How to Save Onion (Allium cepa) Seeds

Seed Saving Guide #2722
Family: Amarlyllidacea
Binomial name: Allium cepa

Flower Type Perfect, self-fertile
Pollination Insect pollinated
Isolation Distance 500m
Population Required for Viable Seeds 5
Population Required to Maintain Variety 20-50
When to Harvest In the second season, when capsules containing seeds begin to split open. Mature seeds are black.
How to Harvest

Cut flower stems (scapes) 20cm below umbels and dry in a paper bag or on a screen for 7-14 days until the seed head is dry. Gently rub capsules to release the seeds.

How to Clean

Screen or winnow to remove chaff if required.

Image of Seeds Onion (Allium cepa)

A cold period of at least 8-10 weeks below 10°C is required for plants to produce seed.

What is Seed Saving?

Seed saving is the practice of collecting and storing mature seeds from open-pollinated plants. By allowing plants to reach full maturity and harvesting the seeds, they can be cleaned, dried, and stored for future use. 

  • To learn the techniques and methods needed to save seeds in your garden, we recommend reading our seed saving series.
  • To view a combined table of all our seed saving guides view our Seed Saving Chart.
  • To browse our seed saving guides individually click here.