Leek (Allium ampeloprasum var. porrum)
11 sources cited · Verified
The short answer
- Sow
- Mid February to mid June
- Plant out
- Early May to mid July
- Ready in
- 60–180 days
- Site
- 6+ hours of sun, soil pH 6–6.5
- Biggest risk
- Allium white rot
In the UK, leeks are sown mid February to mid June, planted out early May to mid July, and are ready to harvest 60–180 days after sowing.
Leeks (Allium ampeloprasum var. porrum) — Hardy biennial grown as an annual.
Core growing advice on this page is checked against named horticultural and university-extension sources — see References.
Watch: Growing Leeks at Home
A quick SoilCommander video on growing leeks at home in the UK — from sowing and transplanting to earthing up for a long white shank.
At a Glance
Quick Facts
| Factor | Value |
|---|---|
| Soil pH | 6 - 6.5 |
| Sunlight | 6-10 hours direct sun |
| Germination temp | 10C |
| Optimal growing temp | 18-24C |
| Minimum survivable temp | -5C |
| Time to harvest | 60-180 days |
| Soil texture | RHS: improve soil by "digging in two bucketfuls of garden compost or well-rotted manure per square metre/yard". |
| Drainage | RHS: "Choose a sunny spot with free-draining soil". |
| Lifecycle | Hardy biennial grown as an annual: the blanched shank is harvested in the first season and stands through winter frosts. Plants flower and set seed only in a second year after cold; the crop is very frost-hardy and is not lifted for storage but left in the ground until needed. |
| Edible parts | stems (white base/shank), flower buds (scapes) |
Regional Planting Calendar
| Region | Sow | Plant out |
|---|---|---|
| Southern England | mid February to mid June | early May to mid July |
| Northern England derived | mid March to late June | late May to late July |
| Midlands derived | early March to mid June | mid May to mid July |
| Scotland derived | early April to late June | early June to late July |
Rows marked derived are interpolated between regions our sources do state, because no source we consulted gives a figure for that region specifically. They are deliberately wider to reflect that uncertainty.
Southern England - detail & sources
Sow leek seed indoors from late winter (keep above 10C) or outdoors from March; transplant pencil-thick plants from about May, and start pulling from late summer with hardy late cultivars standing through winter into spring. Southern England has the UK's earliest soil-warming and last frosts (Met Office), so the earliest sowing and transplanting apply here.
Northern England - detail & sources
DERIVED: about four weeks later than southern England for the earliest sowing and transplanting, reflecting the Met Office south-to-north warming gradient. Hardy leeks overwinter well even in the north.
Midlands - detail & sources
DERIVED: sowing and transplanting run roughly two weeks later than southern England because the Midlands warm and pass the last frost later (Met Office south-to-north gradient). Leeks still stand through the winter for a long harvest.
Scotland - detail & sources
DERIVED: the latest UK start - sow from about April and transplant from early June, as Scotland is slowest to warm (Met Office). Very hardy leeks are well suited to Scottish winters and give a valuable late crop.
Soil & Growing Conditions
Growth Stages
| Stage | BBCH | Notes |
|---|---|---|
| Sowing & Germination | 0 | Leeks are grown from seed. SOWING DEPTH: sow seed 1.5cm (about half to three-quarter inch) deep - indoors in modules or trays in late winter (keep above 10C/50F), or outdoors from March to April in a shallow drill, watering the base first and sowing thinly, with rows about 30cm (12in) apart. Later sowings in May-June give leeks for winter and spring. Grow the seedlings on until they are about 20cm (8in) tall and pencil-thick, ready to transplant (roughly eight weeks from an indoor sowing). |
| Transplanting & Establishment | 3 | This is the step that gives leeks their long white shank. When seedlings are pencil-thick, lift them and trim the roots to about 2.5cm (1in). PLANTING DEPTH & SPACING: with a dibber, make holes about 15cm (6in) deep and 5cm (2in) across, spacing them 15-20cm (6-8in) apart in rows 30cm (12in) apart. Drop one leek into each hole and "puddle in" by filling the hole with water - do NOT backfill with soil; the loose hole blanches the lower stem white as it grows. Water the young plants until they are established, then keep the bed weed-free so the shallow-rooted leeks are not crowded. |
| Shank Development & Blanching | 7 | Over the following months the shank thickens and lengthens. To lengthen the white (blanched) portion, draw dry soil up around the stems several times through the season (earthing up), taking care not to let soil fall into the centre of the plant. Water only during prolonged dry spells once established - leeks are shallow-rooted and drought reduces yield - and keep weeding. Watch for orange leek rust on the leaves and cover with insect-proof mesh where allium leaf miner or leek moth are a problem. |
| Harvest | 8 | Leeks can be harvested at any size: pull baby leeks from late summer, or leave plants to reach full size. They do not need lifting for storage - being very frost-hardy, they stand in the ground and are lifted fresh as needed, with hardy late cultivars cropping right through winter and into spring. Gently lift each plant with a fork rather than pulling, to avoid snapping the shank. Days from sowing to first harvest range from about 60 (baby leeks) to 180 or more for full-sized winter leeks. |
Harvest & Storage
Diseases
Pests
Companion Planting
Leeks, Seed to Harvest
References
-
Tier 1. Primary UK source: sow 1.5cm deep indoors late winter (>10C) or outdoors Mar-Apr, rows 30cm; transplant pencil-thick into dibber holes 15cm deep x 5cm, 15-20cm apart, rows 30cm, puddle in and do not backfill (blanches shank); earthing up; water in dry spells; harvest any size from late summer, standing through winter into spring; leek rust, leek moth, allium leaf miner.
-
Tier 1. US extension corroboration: leeks need regular watering throughout growth (shallow rooting, drought reduces yield), transplanting from seedlings, and blanching for a longer white shank.
-
Tier 1. Host-specific: leek is a principal host of Puccinia rust; orange pustules, heavy attacks cause yellowing and dieback.
-
Tier 1. Host-specific: serious soil-borne disease of onions, garlic and leeks; sclerotia survive 15+ years; no chemical control for gardeners.
-
Tier 1. Soil-borne Fusarium rots the basal plate of alliums; worse in warm soils.
-
Tier 1. Peronospora destructor foliar disease of alliums favoured by cool, wet, humid weather.
-
Tier 1. Host-specific pest: caterpillars tunnel into leaves and shanks of leeks (a principal host); southern/eastern England and spreading.
-
Tier 1. Host-specific pest: larvae mine leaves; secondary rots make the crop inedible; widespread across England since 2002.
-
Tier 1. Host-specific pest: maggots damage roots and stems of alliums; leeks generally less affected than onions.
-
Tier 1. UK climate context for the south-to-north spring gradient used to derive regional sowing/transplanting windows.
-
Tier 1. International agronomic ranges (temperature, pH) for the leek group.
11 independent sources are cited for this crop. Where they disagree - soil pH is the clearest case - every figure is preserved rather than averaged into false precision.
Frequently Asked Questions
When should I plant leeks out in the UK?
In southern England, from early May. In northern England and Scotland, wait until late May. Treat these as a guide rather than a fixed date — the governing rule is to plant out only once frost risk has passed and temperatures are reliably warm enough.
When do I sow leeks?
Sow mid February to mid June, at around 10°C for germination.
How long do leeks take to grow?
Typically 60–180 days, depending on cultivar and growing conditions.
What soil pH do leeks need?
A pH of about 6–6.5. That span reflects genuine variation between the authorities we cite rather than a single agreed figure — the References section lists each source's exact range.
What problems affect leeks?
Our data links 4 diseases and 3 pests to this crop. See the sections above for each one and how to manage it.
Plan next season before the problems start
Most of the advice on this page comes down to timing and spacing — sowing at the right moment, rotating beds, and giving plants enough airflow. The UK Garden Planner lays your plot out month by month so those decisions are already made before the season starts.
Get the UK Garden Planner →Instant PDF download · Written for UK growing conditions
Last verified 2026-08-06
How To Grow Leeks In The UK
To grow leeks in the UK, sow seeds in late winter or spring, grow seedlings on until they are sturdy, then transplant them into prepared soil with enough space to thicken. Keep leeks watered in dry weather, weed around young plants, and harvest from late summer through winter depending on the variety and sowing time.
For detailed month-by-month timing, see when to plant leeks in the UK. Use the UK Vegetable Garden Planner PDF to track sowing dates, transplanting dates, bed positions, and harvest notes.
Tools That Help With This Crop
Use these links when the guide moves from reading into sowing, planting, watering, and keeping the crop healthy.
Plan the next step
Use the printable UK Vegetable Garden Planner to turn this guide into sowing dates, bed layouts, and weekly garden tasks.