When to plant
Start seeds indoors 10–12 weeks before last frost. Transplant outdoors 4–6 weeks before last frost. Leeks are extremely cold-hardy and can stay in the ground through hard frosts. A long-season crop (100–130 days to maturity). One of the best cold-weather crops.
Soil & site
Rich, well-drained soil with high organic matter. pH 6.0–7.0. Work in generous compost. Leeks are traditionally hilled (soil mounded around the shank as they grow) to blanch and extend the white edible portion. Plant transplants in a deep trench (6 inches) to naturally blanch the shank.
Feeding
Heavy feeder with a very long growing season. Apply nitrogen-rich fertilizer every 3–4 weeks from spring through midsummer. As fall approaches, reduce nitrogen and use a more balanced formula. Consistent feeding throughout the long growing season is what produces large, tender shanks.
Common problems
Leek rust (orange pustules on leaves — mainly cosmetic). Thrips cause silvery streaking. Onion fly maggots. Allium leaf miner. Generally a tough crop with few catastrophic problems.
When to harvest
Leeks are ready when the white shank is at least 1 inch in diameter. Most varieties reach 12–18 inches tall when ready. There is no single precise ready moment — leeks can be harvested at almost any size. They hold in the ground very well and can be harvested as needed over months.
How to harvest
Use a garden fork to loosen the soil beside the leek, then pull upward with a twisting motion. For very deep-planted leeks, dig rather than pull to avoid breaking the shank. Trim roots and remove the dark outer leaves. Leave remaining plants in the ground to harvest as needed through fall and winter.
Storage & use
In the ground with mulch protection: several months through fall and early winter. Refrigerator: 2–3 weeks. Freeze: clean, slice, blanch 30 seconds, freeze. Leeks must be washed very thoroughly — grit collects between the leaf layers.
Companion planting
Leeks and carrots are mutually beneficial — they repel each other's key pests.
Useful for growing leek
A few things that make this one easier — chosen for this plant, not a generic list.
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