Like most forms of onion, leeks have been grown since ancient limes. They were probably derived from Allium ampeloprasum, which grows in the Near East and in countries of the Mediterranean littoral. Its traditional connection with Wales arose because Welshmen were said to have worn leeks in their hats in a battle against the Saxons in AD640 to distinguish them from their enemies.
Although leeks belong to the onion family, they do not have such a pronounced basal swelling nor the pungent flavour and smell of the other culinary members of die genus. They consist of cylinders of tightly wrapped leaves, white where they have been blanched and green above soil level. It is the white section that is mainly used. Unlike the other culinary onions, which are mainly used as flavourings, leeks are used as a vegetable in their own right in a wide range of dishes and soups. They can also be used, of course, as a simple vegetable accompaniment.
A wide range of varieties is available, some are’ hardier than others (those with bluer leaves tend to be hardier), and some are ready earlier, while others stand better until spring. Some varieties have been bud specifically for their appearance on the show bench.
Cultivation
Leeks like an open, sunny position and a rich, fertile soil that is reasonably free draining. Dig well-rotted organic compost into the soil in autumn for planting in spring. Leeks like a long growing season, so start them off by sowing in nursery-bed rows in early to mid-spring. Sow thinly in drills 1cm in deep and 15cm apart if you need more than one row. Transplant when the seedlings are 15-20cm high, which will be two or three months after sowing. Water the row the day before lilting and then dig out in batches with a hand fork. Plant into their permanent rows using a dibber. The plants should be 15cm apart and the rows should be 30cm apart. Make a hole about 15cm deep and drop the leek in so that about 5cm of the leaves show above the soil. Do not fill in the hole with soil, but fill it with water. This will wash sufficient soil around the roots.
As the leeks grow, earth (hill) them up by pulling soil up around the stems to blanch them. Alternatively, plant the leeks in the bottom of a trench and gradually fill the trench as the leeks grow. Keep weeded and watered in the early stages of growth.
Harvesting
Leeks can be lilted for use it any time between early autumn and late spring. Dig them out with a fork. Autumn varieties are not as hardy and should be harvested before midwinter.
Storage
Leeks are generally hardy and can be left in die ground until they are required. In cold areas they can be covered over with a cloche. They are best used fresh from the ground, but they can be dug several days before use and kept in a cool place. There is no method of storing leeks out of the ground. If the piece of ground they occupy is needed for some other purpose in the spring, then they can be lilted and heeled in elsewhere until they are needed. Simply dig a trench and insert the leeks to die same depth as they were in their original planting position. Dig them up as and when they are required.
Pests and diseases
Leeks are not usually troubled by pests and diseases. Rust is the most likely problem. Infected plants can be burned or destroyed; it the rust is not too severe it can be ignored, although it is best to plant leeks elsewhere for the next year. Other onion pests and diseases may occasionally be a problem; destroy any affected plants.
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