Leek
Allium ampeloprasum
Mild standing allium that confuses carrot fly all season.
Spacing & sowing
- Plant spacing
- 5.9 in
- In-row spacing
- 4.7 in
- Between rows
- 11.8 in
- Square-foot density
- 9 per square
- Sow depth
- 0.4 in
Calendar (from your frost dates)
- Sow indoors
- 56 days before the last spring frost
- Sow direct
- 14 days before the last spring frost
- Plant out
- at the last spring frost
- First harvest
- 120 days after the last spring frost
- Harvest ends
- 30 days after the first fall frost
Growing
- Type
- Vegetable · Grown as an annual
- Botanical family
- Allium (onion family)
- Sunlight
- Full sun to part shade
- Watering
- Moderate
- Soil
- Deep, rich, well-drained
- Feeding
- Bulbs & roots
- Frost tolerant
- Yes
- Season
- Cool Season
- Harvest type
- Single Harvest
- Start from
- seed
Growth stages
- 0 d Sow seeds
- 14 d Germination
- 200 d Harvest
Harvest
- When
- Earlies are ready from early autumn, about 25–30 weeks after sowing; hardy maincrops stand in the ground all winter and are lifted as needed into early spring. Lift the last of them before they bolt as days lengthen.
- What to look for
- Ready once the white shaft is 2–3 cm thick — though anything from pencil-thick upward is usable, and leeks hold in the ground for months without spoiling. A hard, round flower stem rising in the center (spring) means eat immediately or compost.
- How to harvest
- Push a fork in vertically alongside the row and lever the leek out — never pull by the leaves, which simply tears the plant in half and leaves the shaft in the ground. Trim roots and the top third of the leaves outside; soil hides deep in the leaf sheaths.
- How often
- Lift as needed through autumn and winter — the ground is the perfect store. Take the thickest first; before a forecast deep freeze on heavy soil, lift a week's supply and heel it into a box of compost by the door.
- Storing the crop
- Best stored where they grew; once lifted they keep 1–2 weeks in the fridge, roots on, loosely wrapped. Heel surplus into a trench or bucket of damp compost in a cool spot for weeks. Sliced and washed leeks freeze acceptably for cooking.
Pests & problems
- Onion fly & leek moth Maggots burrow into the base of onions, leeks, and garlic; leaves yellow and droop. Grow alliums under insect mesh and rotate to fresh ground each year.
- Thrips Minute slender insects that leave silvery flecking and distortion on leaves and flowers in hot, dry spells. Keep plants watered and use blue sticky traps under glass.
- Root & crown rot Roots or crown turn brown and mushy in waterlogged soil or compost; the plant wilts even when wet. Improve drainage, water less, and pot up only into free-draining mixes.
- Rust Orange-brown powdery pustules on leaf undersides, weakening the plant over the season. Remove affected leaves, avoid overhead watering, and clear all debris in autumn.
Garden allies
Beneficial predators that hunt this plant's pests — grow their favourite flowers nearby to recruit them. companion plant
- Beneficial nematodes Steinernema & Heterorhabditis spp.Hunts Onion fly & leek moth
Microscopic worms watered onto damp soil that hunt down soil-dwelling grubs and release a bacterium that kills them within days. Timing is the whole thing: warm, damp soil and a small target grub, which means late summer for most of what they are used against.
- Big-eyed bug Geocoris spp.Hunts Thrips
A stubby 3 mm bug with enormous wrap-around eyes, working the soil surface and the low foliage for aphids, mites, thrips and insect eggs. It is the main natural check on chinch bugs in a lawn and it is killed outright by insecticide.
- Damsel bug NabidaeHunts Thrips
A slender, mantis-armed bug that grabs aphids, small caterpillars, and thrips in low crops and meadowy edges. Leave a strip of unmown grasses and flowers for it to overwinter in.
- Green lacewing Chrysoperla carneaHunts Thrips
Its bristly larvae — "aphid lions" — impale aphids, mealybugs, thrips, and mite colonies, eating hundreds a week. Adults feed on nectar and pollen from small open flowers and overwinter in hollow stems left standing.
- Hoverfly SyrphidaeHunts Thrips
Bee-mimicking flies whose legless larvae graze aphid colonies clean while the adults pollinate. A ribbon of shallow, nectar-rich flowers kept in bloom all season recruits wave after wave of them.
- Minute pirate bug Orius spp.Hunts Thrips
A pinhead-sized true bug that is the best natural check on thrips, and happily spears aphids, mites, and insect eggs too. It needs pollen when prey is scarce, so keep something flowering nearby.
- Predatory mites Phytoseiulus & AmblyseiusHunts Thrips
Fast orange mites that hunt spider mites egg-by-egg, and cousins that clear thrips and fungus-gnat larvae. Sold as a biological control for greenhouses; outdoors they follow humidity — mist and mulch, don’t dust with sulfur.
- Rove beetle StaphylinidaeHunts Onion fly & leek moth
Slim, quick beetles with short wing cases that hunt in soil and litter, taking root-fly eggs and larvae, fungus-gnat larvae, and mites. Mulch and undisturbed ground keep them resident year-round.
Germination & growth
- Germination temp
- 54–72°F
- Min soil temp
- 43 °F
- Photoperiod
- long day
Companion planting
Good neighbors
Did you know?
The leek is the national emblem of Wales, worn on St David's Day.
The Cottage Garden Companion — the gardener's herbarium at cottagegardencompanion.com