Leeks are biennial and will cross-pollinate with other varieties of leek. To prevent this it is best to grow just one variety. They will not cross with other members of the Allium family to which it belongs. Leeks should easily over winter outside.

Plant and grow the leeks during the first year just like you would for eating. If you find any plants that are bolting remove them. Select at least 15-20 plants to maintain a good genetic diversity. These plants need to look healthy and so remove any that look stunted in growth or have any significant discolouration on the leaf.

In the second year tall round flower spikes will start to form. The flower-heads when they emerge are in its own sheath. The plants will need staking at this point with canes to prevent the wind from breaking them.

Leek seed ripens later than other members of the Allium family like for instance onions. Consequently there is not enough time in the autumn as the weather changes for the seed to dry out. So cut the seed head along with its stem leaving about 25cm. Bring them inside to a dry warm yet airy room and spread them out on a sheet to fully dry out so that the seeds can readily separate from the capsules. More information on seed drying can be found under our section ‘Seed Cleaning and Drying’ on our website.