Growing and Saving the Seed Of Leeks

A member of the onion family, leeks are grown for a tall and thick “stem” which is actually a bundle of flat leaves. Leeks are very cold hardy and more mellow in flavor than onions, and they make excellent soups, gratin and so much more.



Leeks are believed to have originated in the Mediterranean. They were depicted on the walls of ancient Egyptian tombs. The emperor Nero, who was referred to as “the leek eater,” loved leeks in soup and believed that they improved his voice. Leeks are a major part of the culinary heritage of Wales. 


  • Many culinary uses




  • Seeds do not need excessive heat or sunlight to germinate.
  • Temperatures of 60-65 F are best.
  • Sow seeds ½ inch in pots at least six inches deep. This is crucial; do not sow in shallow pots. 
  • Seeds germinate in 7-14 days.

  • Ideal germination temperature is 60-65 F.




  • Harden off plants outside once soil can be worked in spring.
  • Dig a trench 6 inches deep and place seedlings 6 inches apart in a row at the bottom of the trench.
  • As the leeks grow, gradually fill in the trench; this is called blanching and it will keep the “stems” white and tender.
  • Leeks need rich, finely worked garden soil.


  • Leeks are relatively pest and disease-free.
  • The biggest challenge is to keep them free from weeds, as all onion family members are terrible at competing with weeds.
  • Try mulching with plastic mulch or a thick layer of other mulch to keep the weed competition down.


  • Leeks will not cross with any other allium (onion) family members, but they do require 1 mile isolation from other leek varieties for seed saving.
  • Leeks are biennial.
  • In mild winter areas, simply allow them to overwinter and protect with mulch if temperatures below freezing are expected.
  • In cold climates, leeks will need to be dug up and stored in a root cellar. Replant in spring, and allow them to flower.
  • Leek seeds can be stored for up to 3 years, but germination is usually only as high as 50 percent.