[header] How to save onion seeds [title] Plant onions, and leave them in the ground for two years. [step] Watch for flowers and then seed heads to form during the late summer of the second season. [substeps] You may wish to plant extra plants if you want onions to eat during the first season. 
[title] Wait for the seed heads to dry. [step] Most of the flowers will be dry, and the seeds will begin to fall out on their own.