How to grow leeks
SOIL
Leeks thrive in moist clay or silty loam, enriched with compost and animal manure. They dislike compacted, heavy or poorly drained soil.
TRANSPLANTING
Transplant seedlings when they're 2025cm high. Water thoroughly, well before planting. Trim off a third to half of the leaf. Space 15cm apart in rows 30cm apart, for easier weeding. If you like small succulent leeks, space them at 7.5cm and harvest every other leek while they are small.
BLANCHING
To get the long, white stems, ‘blanching' needs to begin when the seedlings are transplanted. Without it, the shanks will come out short and mostly green. There are two methods.
1 Use a dibber to dig a hole 15-20cm deep and drop the plant into it so the roots are resting on the bottom of the hole and the tips of the leaves are just showing above ground level. Water gently so the soil washes into the hole and covers the roots. Do not try to cover the roots with soil, or firm them in. Don't worry if the leek doesn't stand upright – it soon will. As the seedling grows, the hole will fill in by watering and natural erosion. This helps to thicken up the stems, and blanche them at the same time.
2 Dig a 30-40cm deep trench and fill it two-thirds full with a mix of manure, compost, and topsoil. Set the plants in 10cm deep holes in the bottom of the trench, so the roots grow into the enriched soil, rather than the subsoil below. When the plants are around 15cm high, push fine, dry dirt up around the stems, 5-7cm at a time, every so often. Avoid dropping soil between the leaves, and don't 'earth up' too quickly or they may rot. Stop when plants reach maturity.
HARVEST
You can start harvesting as soon as the shanks reach 1-2cm in diameter. If plants are started in early summer and fed adequately, they should reach 8cm diameter by winter.
Place a fork under the roots. Lever the leek up, being careful not to damage or break the stems.
In spring, the remaining leeks can be dug up and heeled-in, in a cool, shady spot. This delays flowering, prolongs harvesting, and releases garden space for spring crops.
HOW TO PREPARE
One leek is good for one to two people. Trim off the root ends and most of the coarse green leaves. Remove the outer skin and any discoloured layers. Wash under running water until all traces of dirt are removed.