The leek is a member of the onion family, but is milder than either onions or garlic. Unlike onions or garlic, leeks do not form bulbs or produce cloves but develop an edible 6 to 10 in. (152mm – 254mm) long round stem as much as 2 in.(50mm) in diameter.
The leek has leaves very similar to garlic. They are flat rather than round and hollow like onion leaves. Leeks are undoubtedly one of the easiest vegetables to grow. They can be made into soups, stews, and broths with, or in place of onions.
Leeks do perfectly well in any soil, though good, deep loam is best. It is important that they have well-drained soil; they will not tolerate stagnant soil conditions. Add lime as a surface dressing before planting out.
To prepare the ground, dig in some well-rotted manure or compost at the rate of one bucketful to 8 sq. yds. bury it down to a spades depth. Two weeks before planting add fish and bone manure at a rate of 3 oz. (90g) to the sq. yd.
Late March make shallow drills ½ in. (12mm) deep and 6 in (15cm) apart, sowing the seeds thinly. Earlier sowings can be made as early as January if the seeds are sown in trays and kept in the greenhouse at a temperature of
55 deg F.(13 deg C.).
Keep them in the greenhouse until March then begin to harden them off in a cold frame; they can then be planted out either late April or early May.
Leeks can be planted into trenches or at ground level. To plant in trenches dig out to 1 ft. (30cm) deep and 1 ft. (30cm) wide adding manure or compost to the trench to a depth of 4 in. (101mm). Put back 3 in. (76mm) of the soil leaving the remainder on either side of the trench.
Insert the plants 1 ft. (30cm) apart down the centre of the trench, burying the roots about 1 in. (25mm) deep; the trenches should be 1 ½ ft. (45cm) apart. The plants will now be standing at a lower level than the surrounding soil.
Keep down the weeds with a hoe. Three weeks after planting apply fish or poultry manure at the rate of 2 oz (60g) to the yard. Cut off any flower stems that appear. Make sure that they have enough water; in dry weather, they must be watered allowing the roots a thorough wetting.
Where leeks are grown in trenches they need to be gradually earthed up. Add about 1 in. (25mm) of soil to the trench a month after planting and this should continue on a monthly basis taking the soil from either side of each trench; do not bury the leaves themselves.
It is a good idea to wrap corrugated cardboard around the stems, loosely tied with soft twine before earthing up; this procedure helps to prevent grit from collecting between the leaves.
The first leeks are normally ready during October. Loosen the soil around the stem with a fork before pulling it out. Keep those leeks that are not yet ready covered so that they remain in the dark.
When the roots are cut off the vegetable, put them onto the compost heap, for they make excellent compost.