Leek

Light and exposure

The leek likes full sun, but tolerates well a slightly shaded position for part of the day. What it needs above all is space and a clear bed to develop its long white shaft.

As it occupies the ground for long months, including all winter, choose a spot that will not get in the way of the following spring crops. A bed accessible even in wet weather makes harvesting easier through the bad season.

Watering

The leek appreciates soil that stays cool. Water regularly during the summer, especially after planting and during dry spells, so that it swells without check. Soil that dries out too much gives thin, tough leeks.

In autumn and winter, the rain of our regions is amply sufficient, and watering becomes needless. The established leek then makes do with the soil’s natural moisture, abundant here in this season.

Soil and repotting

The leek likes deep, loose and rich soil that holds coolness. Soil enriched with mature compost before planting suits it perfectly. It dreads soil that is too stony, which deforms the shaft.

In the heavy, damp soils of the region, work the bed well and deeply to loosen it and prevent water from stagnating around the roots in winter. A slightly raised bed helps drainage without penalising the crop.

Temperature and humidity

The leek is one of the hardiest vegetables in the garden. It withstands without trouble frosts of several degrees below zero and stays edible all winter in the open ground. The cold only improves its flavour.

This is precisely what makes it the ideal winter vegetable in the Herve climate. Where the tomato and the bean have long since disappeared, the leek holds firm in the cold and the damp. Only really harsh winters, with the soil frozen deep, complicate lifting: a good mulch of leaves or straw at the base then lets you harvest even in freezing weather.

Pruning and upkeep

The leek is not pruned, but it is earthed up. Earthing up consists of drawing the soil around the shaft as it grows, which lengthens and blanches the tender, tasty lower part. Earth up gradually, in two or three goes, taking care not to let soil fall between the leaves.

Another method is to plant deep in a hole made with a dibber, without filling it back in, to obtain a long white shaft naturally. At planting time, the foliage and roots of the young plants are often shortened by a third to encourage them to take.

Pests and diseases

The great enemy of the leek is the leek worm, in fact the larvae of two pests: the leek moth and above all the leek miner fly (Napomyza gymnostoma), whose larvae dig galleries in the shaft and make it rot. The best remedy is preventive: an insect-proof net laid over the bed stops the flies from laying eggs, at the two flight periods, in spring and late summer.

Watch too for rust (Puccinia allii), which covers the leaves with orange pustules in mild, damp weather, without really compromising the harvest, and downy mildew in case of excess moisture. Crop rotation, by not putting alliums back in the same place for three years, limits all of these problems.

Propagation

The leek is multiplied by sowing. Sow in a nursery, in a plug or in a seed tray, from February-March under cover, or in April in the open ground. When the young plants are the thickness of a pencil, around May-June, lift them and transplant them in place, dipping the roots in a puddling mix if you wish. It is this transplanting that gives fine shafts.

To harvest your own seed, let a few plants run to flower in the second year: the leek is biennial and forms a large spherical umbel that produces black seeds. Harvest them when the head dries, and keep them dry. They keep poorly, two or three years at most.

Month-by-month care calendar

Green Hub tips

• Transplant deep in a dibber hole without filling it back: the shaft lengthens and blanches on its own, without earthing up.
• An insect-proof net from planting to autumn is the only real defence against the leek worm.
• Mulch the base before the hard cold: the soil stays loose underneath and you lift even when it freezes at the surface.
• Do not harvest everything at once: the leek waits in the ground all winter and improves with the frost.