Grow and Save Leek Seeds

How to Plant, Grow, and Save Seeds from Leek (Allium ampeloprasum)

Leek has been used as a culinary crop for at least 4,000 years. Enjoy this historic Allium in your garden and try your hand at biennial seed saving.


Sow leek seeds indoors 8-10 weeks before the last frost date. Plant leek seeds ¼” deep into flats. Seeds will germinate in 5-7 days. Seedlings can be transplanted outside as soon as the risk of hard frost has passed. When transplanting leeks into your garden, space them 6” apart.

Leeks can suffer from downy mildew, white rot, and leaf blight. Take care to rotate plant families in your garden to prevent diseases.

Harvest leeks when they reach a diameter of between ½”-1 ½”. Take care to thoroughly wash your leek plants before cooking with them; dirt can accumulate between their tall leaves.

Eating and Storing

Leek can be used in many recipes that call for onions. The flavor and texture of leek holds up to a lot of cooking, so use leek in soups, stews, and other simmered dishes. Whole leeks will store for weeks in a refrigerator and months in a root cellar.

Saving Seeds

Leek is a biennial crop. Biennials typically do not flower in their first growing season. They must first experience cold weather before they flower, set seed, and die in their second growing season.

When saving seeds from leek, separate varieties by at least 500-1,600 feet in their second year. To ensure viable seeds, save seeds from at least five plants. To maintain a variety over time, save seeds from between 20-50 plants.

To produce seed from leeks, select several perfect leeks and store them through winter. Ideally, store leeks in a cool, dry space away from sunlight. Replant leeks in early spring using the same spacing used in their first year of growth. Staking leeks to prevent lodging during flowering is recommended.

After the plants bloom and seed heads begin to dry, gather the heads in a paper bag and shake the seeds free. Allow the seeds to air-dry for a few days before storing the seeds in a cool, dry place. Leek seeds will remain viable in cool, dry storage for a couple of years.

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