How Do I Get a Longer White Shank on My Leeks?

The prize part of a leek is the long white shank — the pale, tender, mildly flavoured section below where the green leaves branch out. Many home-grown leeks end up with disappointingly short white sections and long green shanks, which are edible but tougher, stronger in flavour, and less impressive. Achieving a long white blanched shank is a technique, not a variety choice, and once you understand how blanching works you can apply it to any leek variety you grow.

The principle — darkness creates white

The leek shank turns green when exposed to light, through the same chlorophyll formation that colours any plant tissue in sunlight. The white, blanched section is simply the part of the shank that has been excluded from light — buried in soil, surrounded by a collar, or packed with compost. The greater the length of shank you keep in darkness from the start of growth, the greater the length of white shank at harvest. This is the entire basis of the blanching technique: maximise the soil coverage over the lower shank at every stage of growth.

Step 1 — Deep planting

At transplanting time, use a large dibber to make planting holes 15–20 cm deep. Drop each transplant into the hole so that only 4–5 cm of leaf tip is visible above ground level, then water in without backfilling. The soil will naturally crumble in over the following days. This deep initial placement means the entire length of the shank from root to the point where leaves branch is already in darkness and blanching from day one.

Step 2 — Regular earthing up

As the leek grows, the shank extends above the original planting level. Every three to four weeks during the growing season, draw soil up around the shank to just below where the leaves branch. Use a hoe between rows and your hands around individual plants — be careful not to push soil into the fan of leaves at the top. This progressive earthing up extends the blanched section upward as the plant grows. Three or four earthing-up operations through the season can produce a white shank of 20–25 cm.

Using collars for additional length

For very long shanks, cardboard or plastic tubes (cut from old drainpipe) placed around the shank before earthing up give a starting form that allows soil to be built up higher without collapsing inward. This technique is mainly used by show growers aiming for very long shanks; for everyday growing it is unnecessary.