Guide to Growing Leeks
Guide to Growing Leeks
Leeks – Allium porrum
The leek has been in cultivation for many centuries and was held in high esteem by the ancient Egyptians. Nero is said to have valued it as a voice improver. It is the national emblem of the Welsh, and as a member of the onion family is reckoned to have health promoting qualities. One reason for its popularity is that it is very hardy, which is why leeks have always found favour in colder areas.
Leeks will grow in almost all soils which are moisture retentive, without being badly drained. The plants are best grown in trenches. These should be 25 to 30cm deep, and 30cm wide, for a single row or 45cm wide for a double row. Work in decayed manure,or other , on top of which place a layer of fine to bring the depth of the trench to 15cm. Do not use fresh manure which is liable to lead to coarse, rough growth instead of the needed tight thick stems. Where bulky manure is not available, use fish manure or bone meal, 2 or 3oz to the square metre.
The earliest sowing can be made in a temperature of 15 to 18°C using trays or pans of the John Innes seed compost. When the can be handled, prick them out keeping them in full light near the glass in a temperature of around 12°C. Subsequently move the plants to the cold frame for hardening of before planting outdoors in spring.
Alternatively, sow under cloches or frames in early spring and after germination the young plants can be left uncovered. Once they are 20 to 23cm high, move them to their final positions.
The earliest leeks can be grown on the flat. For these, make 15cm deep dibber holes 15 to 20cm apart, and drop the seedlings into them. Do not fill the holes with soil, instead, pour a little water into each hole. This will wash some soil over the roots. Fill up the holes as growth develops, although they often rill naturally from the effects of weather. If the foliage droops or if the tips of leaves wilt or lie on the soil, cut them back or worms may pull them into the soil and upset the plants.
Once they are growing well they can be helped by dusting an organic fertiliser along the rows at the rate of 1-1/2 to 2oz to the metre run. Alternatively apply liquid manure at fourteen day intervals. Keep downand nip out flower stems if seen.
In trenches, the earthing up process will normally begin about a month after planting, soil being drawn up at intervals of three or four weeks. Soil used for earthing up should be fine so that the plant stems are covered evenly. Some gardeners place rings of corrugated paper around the stems before earthing up. This stops the soil from falling between the leaves and prevents grittiness when the leeks are cooked.
Very late planted leeks can be earthed up, for this speeds the blanching process. Moisture must be kept out of the centre of the plants which need regular watering, liquid manure being beneficial. Any still in the ground in the spring, should be heeled in near a north wall or hedge. This releases the ground for another crop and prevents the plants from running to seed.
For exhibition, leeks require extra cultural attention. The standard is high and 15cm or more, should be the length of the blanched portion of stem. Leek measurement tables are often used and competition is keen. Wide spacing is needed for exhibition plants with some protection where the situation is exposed. Sometimes bottomless stone jars are placed over the plants. These help to increase the length of blanched stem and give protection against winds and frosts.
Varieties include: Musselburgh, thick stems; The Lyon; Prizetaker; Broad London or American Flag and Marble Pillar, a fairly new sort producing long solid white stems. Walton Mammoth is one of the best, with long thick, solid stems valuable for exhibition. Specialist showmen often hold their own stock of which they do not disclose the origin.