| Annual or perennial | Biennial (grown as annual) |
| Difficulty | Easy to moderate |
| Height | 40-60cm |
| Spacing | 15-20cm in rows 30cm apart |
| Harvest window | September to March (winter crop) |
Leeks are the most reliable and rewarding winter vegetable you can grow in Alsace. Hardy enough to survive in the ground through hard frosts, they provide fresh produce from September through to March when most of the garden is dormant. A true kitchen garden staple.
Which variety to grow
Early varieties like ‘King Richard’ or ‘Jolant’ are long, slender, and ready from late summer. Maincrop varieties (‘Musselburgh’, ‘Bleu de Solaize’) are hardier and thicker, ready from autumn through winter. Late varieties like ‘St Victor’ and ‘Jaune du Poitou’ stand through the hardest frosts and are harvested into March. For Alsace winters, choose a maincrop or late variety specifically rated as very hardy.
When to plant
Sow indoors in January-February, or in a seed bed outdoors from March. Transplant to the final bed in May-June when seedlings are 15-20cm tall and about pencil thickness. Plant deeply in a dibbed hole 15-20cm deep – drop the seedling in and water to settle soil around the roots without firming. This blanching method produces the long white shank.
How many to grow
A row of 20-30 plants provides leeks from autumn to early spring for a family. They stand in the ground until needed, so a single sowing covers months of meals. Grow more than you think – leeks are slow to mature and it is easy to underestimate how many you will use.
Conditions it needs
- Sunlight: Full sun to light shade.
- Soil pH: 6.0-7.0
- Soil type: Rich, deeply dug, moisture-retentive. Dig in plenty of compost when preparing the bed.
Container growing
Possible in deep containers (30cm+) but leeks are better suited to the ground given their size and long growing season. If container growing, use a large trough and plant shallowly – the deep-planting method for blanching does not work in shallow containers.
How to care for it
Earth up (draw soil up around the stems) in late summer and autumn to increase the length of the white shank and improve flavour. Water in dry spells during summer establishment. Leeks in the ground through winter need no protection in Alsace – they are extremely hardy.
Propagation
Sow from seed each year – leeks do not divide or take cuttings. If you want to save seed, leave one or two plants in the ground in their second year – they bolt dramatically into tall flower heads, which produce copious seed. The flowers are also beautiful and attract pollinators.
Watch out
Leek rust (orange streaks on the leaves) is increasingly common and can look alarming. It is mainly cosmetic – it affects the outer leaves but rarely damages the edible shank significantly. Remove the worst outer leaves, improve airflow, and avoid overfeeding with nitrogen. The leeks are still usually fine to eat.
Companion planting
Leeks benefit from being near carrots (both deter each other’s main pests). Celery and celeriac are traditional companions. Keep away from beans and peas.
Problems to watch for
- Leek rust: Orange streaks on outer leaves. Usually cosmetic. Remove affected leaves and improve airflow.
- Allium leaf miner: White tunnels in leaves, then maggots in the stem. Cover with fine mesh from March to May and again in autumn.
- White rot: As with garlic – devastating fungal disease. Remove and destroy affected plants immediately.
When and how to harvest
Harvest when the shank is at least 2-3cm in diameter. Use a garden fork to loosen the soil and lift carefully rather than pulling. Leeks left in the ground through winter remain in perfect condition – harvest as needed from September through March.
How to store
- In the ground: The best storage – leave in place and harvest as needed.
- Refrigerator: Trimmed leeks keep for 1-2 weeks wrapped in paper.
- Frozen: Slice, blanch for 1 minute, cool, and freeze in portions for use in cooked dishes.
In the kitchen
Savory
Vichyssoise (cold leek and potato soup – a French classic), leek and potato soup, leek and goat cheese tart, leek gratin, leeks vinaigrette (cooked leeks with a sharp mustardy dressing), leek risotto, leek and butter pasta, in quiches and frittatas. Leeks cooked slowly in butter until silky and sweet are one of the great building blocks of French cuisine.
Sweet
Not typically used in sweet dishes, though leek and honey combinations appear in some traditional preparations.
Drinks
Not used in drinks, but leek-based stocks and broths are outstanding as a savoury drinking broth in cold weather.