Guv's Gardens
Photo: Amada44, CC BY-SA 4.0, via Wikimedia Commons
- Sun
- Full sun
- Soil
- Fertile, moisture-retentive
- Soil pH
- Best at pH 6.0-7.0; tolerates acid, neutral or alkaline soil
- Water
- Water in dry spells
- Hardiness
- Fully hardy crop (RHS H4 rating)
- Height and spread
- Around 45-60cm as a crop; to 90cm-1.2m if left to flower
Guv's tipEarth up your leeks for nice blanched stems. Transplant them in June or July when they're pencil-thick, about 20cm tall.
Through the year
Timings are for the UK as a whole. Northern and exposed gardens often run a couple of weeks later.
When to plant
Sow under cover or in pots Feb-Apr (outdoors Mar-Apr). Transplant Jun-Jul when pencil-thick, about 20cm tall
Harvest or flowering
Harvest Aug/Sep-Mar/Apr depending on cultivar
Pruning
None; earth up for blanched stems
Making more plants
Seed
Watch out for
Allium leaf miner
Look for: Lines of white dots on leaves, distorted foliage, pupae in stems/bulbs
What to do: Cover with insect-proof mesh during adult flight periods (spring and autumn)
Leek moth
Look for: Caterpillars mining leaves, white patches and holes
What to do: Insect-proof mesh, remove affected leaves
Onion fly
Look for: Maggots in bulbs, yellowing and wilting plants
What to do: Crop covers, rotate crops, remove affected plants
Slugs and snails
Look for: Irregular holes in leaves, slime trails, seedlings eaten
What to do: Hand-pick at night, barriers, beer traps, encourage predators; ferric phosphate pellets sparingly
Leek rust
Puccinia alliiLook for: Orange pustules on leaves
What to do: Generous spacing, avoid excess nitrogen; resistant cultivars
Always read and follow the label on any treatment, and check it is approved for use where you live.
Safety and spread
Pets and people: Edible for people (low severity in large quantities). Alliums are toxic to dogs and cats (haemolytic anaemia, per the ASPCA's onion entry)
Weed risk: The crop leek is not listed as an invasive plant in Great Britain (only wild Allium species such as three-cornered leek are listed)
The Plant Doctor and the Guv's book
Printable pest and disease charts with real photographs, and all 50 UK plants in one book.
