Seed Saving from Leeks
Leeks are insect pollinated and will cross with other leek varieties. They are biennial flowering in their second year. Ideally a distance of up to 1600 meters should be observed between two different flowering leek crops. However in more sheltered areas with hedges, trees and other barriers, a shorter distance of 800 meters can be used. To ensure viable seeds, save seeds from at least 5 plants. To maintain a variety over many generations, save seeds from 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. In milder areas leeks can be left in the ground over winter.
Once the first flowers appear, support them with canes, one for each plant. Alternatively support the plants with stakes at each end of the bed and at intervals in the row. Then tie several rows of string along the outside of the crop to keep stems in and supported.
The leek flowers later than onions producing usually just one seed head per plant.
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.