Buy you leek seed here.
Leeks are an indispensable vegetable related to onions and shallots. For a winter crop they are started from transplants by sowing seeds in March or April. They should be ready for planting outside in the garden in June or July. For average size leeks, plant in rows 30cm apart, leaving 15cm between plants within a row. For baby leeks seed can be sown any time and harvested as the size to suit your needs.
Leeks are related to onions and shallots, and are a very versitile vegetable in the kitchen. They are renown for their winter hardiness, and are an indispensable winter vegetable for the home gardener.