Leek

Allium porrum

You can dig leeks from late summer right through winter. Sow them in a seedbed or in pots. When the young plants are about as thick as a pencil, move them into deep holes made with a dibber, a pointed planting stick. Fill each hole with water. Planting them deep gives you a long white stem.

Looking after it

Water: They need normal watering. Water young plants until they are growing well. After that, water only in long dry spells. Water the soil and keep the leaves dry, which helps hold rust back. Feeding: Leeks need rich soil. They stay in the ground for months, so dig in plenty of compost or manure before planting. On poor soil, a nitrogen feed in midsummer helps.

Harvest and keeping

From late summer, lift leeks with a fork as you need them. Take every other one and the rest grow bigger. Late kinds can stay in the ground all winter. Frost makes them sweeter. Leeks keep best in the ground until you need them. Once they are out, keep them unwashed in the fridge and use them soon.

What can go wrong

Leek rust. Raised orange spots appear on the leaves, worst in late summer. Water the soil rather than the leaves and grow a resistant variety if it comes back. Leeks with a little rust are fine to eat.
Allium leaf miner. The first sign is lines of tiny white dots on the leaves. Then small grubs tunnel into the stems, which twist and rot. Cover leeks with fine insect mesh from the day you plant them.
Leek moth. Caterpillars tunnel in the leaves and leave white, papery patches. Cut off the damaged leaves. The same fine mesh keeps the moth out.

Growing facts: RHS, UC ANR and seed-company sowing guides. Leek care: RHS. pH: University of Connecticut extension.