One of the great versatile vegetables for cooler climates. They do best with temperatures between 15 and 25 degrees C. Leeks are an easy to grow member of the Amaryllidaceae family, easier than the onion, not fussy about its soil and can remain in the ground throughout winter until needed, a useful trait as they are one of the reliable performers and give you a harvest when home grown produce is a bit thin on the ground over winter. Grown for their blanched thickened stems (actually elongated leaf bases), their pungent but sweet flavour is great is soups and stews, savoury tarts and flans, as well as raw in salads and other dishes.
Leeks are better grown without enriching the soil. Use a patch in your vegie garden that was enriched last season, if the soil is too heavily manured the leeks will be coarse, tough and too leafy. If the soil needs improving, add compost rather than manure. If you like to follow crop rotation practices, plant leeks after lettuce, cabbage or peas, but avoid potatoes as the soil is too loose and leeks do better planted into a firm base soil. Crop rotation will aid in reducing pests and diseases.
There are two ways of growing your leeks. You can either plants them in individual holes, and then progressively fill the holes in, alternatively you can use a trench.
Planting in holes
Use a dibbler or a trowel and make holes 15cm deep. 5cm in diameter and around 20cm apart. Make sure the holes are vertical and slightly wider at the top than the base. Cut back the seedling roots to around 2.5cm and lightly trim off the top of the leaves. Carefully lower the leek into the hole and fill with water. This will wash enough soil over the base of the plant to hold it in place. Over time gradually fill the hole up with soil to the bottom of the lowest leaves.
Planting in trenches
Dig a trench 30cm deep and 10cm wide. Put 8cm of well rotted compost into the base of the trench and cover with 15cm of topsoil. Carefully plant the leeks absolutely upright and about 10cm apart. Water in by filling the trench with water. Check when water has drained away that your seedlings are still vertical. As the leeks grow gradually fill in the trench to the bottom of the lowest leaves each time. Do not use wet soil (to avoid rot).
Harvest when they are large enough, usually 5-6 months after planting. Use a sharp knife to undercut the roots and pull from the soil. Wash the roots and stem, trim the roots and leaves and store in the refrigerator. Best eaten soon after harvest, but can be stored.