Leek in May: monthly care

Leeks thrive in full sun and prefer rich, moisture-retentive soil. They do best in loam or clay soil that has been well prepared with plenty of organic matter. Before planting, dig over the bed thoroughly and incorporate well-rotted compost or manure to a depth of at least 20 cm. Leeks are heavy feeders and benefit from fertile ground. You can sow leek seeds indoors from late February or directly outdoors from March through May. For transplanting, sow seeds thinly in modules or seed trays and grow on until the seedlings are pencil-thick, usually 10–12 weeks after sowing. Transplant young leeks from April to early June when they're about 15–20 cm tall. The traditional method is to use a dibber to make holes 15 cm deep and 15 cm apart in rows 30 cm apart. Drop one leek seedling into each hole so that only the top leaves show, but don't backfill the hole with soil. Instead, simply water in well—the soil will gradually wash in around the roots. This deep planting encourages a long white shaft, which is the edible blanched stem you're aiming for. Alternatively, plant leeks in shallow trenches 10–15 cm deep, setting them at 15 cm intervals. As the leeks grow, gradually earth up soil around the stems every few weeks to increase the length of the white portion. Water thoroughly after planting and keep the soil consistently moist during the first few weeks while the young plants establish. A mulch of compost around the base helps retain moisture and suppress weeds.

Leeks need consistent moisture throughout the growing season, particularly from late spring through summer when they're putting on growth. Water regularly during dry spells to keep the soil evenly moist but not waterlogged. In clay or loam soils with good structure, once or twice a week is usually sufficient, but increase frequency during hot, dry weather. Reduce watering from autumn onward as growth slows and rainfall typically increases. Feed leeks in May and June with a balanced general-purpose fertiliser or a nitrogen-rich feed to promote strong leafy growth and thick stems. A liquid feed every two to three weeks during this period works well, or apply a granular fertiliser according to the packet instructions. Avoid feeding after midsummer, as leeks need to harden off before winter. Leeks are fully hardy across zones 4a to 10b and will stand in the ground through winter without protection, making them an invaluable fresh vegetable from autumn to early spring. In fact, many varieties improve in flavour after a frost. Mulch around the base with compost or straw in autumn to suppress weeds and retain moisture. Common pests include leek moth, whose larvae tunnel into the leaves and stems, and onion fly maggots, which damage roots. Cover crops with insect-proof mesh from May onward to prevent egg-laying. Rust (orange pustules on leaves) can be a problem in humid conditions—ensure good spacing for airflow and avoid overhead watering. Rotate your leek bed each year to reduce the build-up of soil-borne pests and diseases.