Harvest leeks when they are big enough to use. Most leeks mature 100 to 120 days after sowing seed, but a few varieties mature in as few as 60 days.
Some varieties mature at ½ to ¾ inches in diameter; others can grow to 1 inch (2.5 cm) or more in diameter.
When to Harvest Leeks
- A leek is ready for harvest when its white stem or shaft is 3 inches (7 cm) long or greater.
- Harvest leeks before they start to widen too much at the base; don’t allow leeks to form bulbs.
- The top growth of a leek—called the flag—should be dark blue-green at harvest. Unlike onions and shallots, leek tops do not die back as the plant matures.
- Leeks can be harvested from late summer to early spring depending upon the variety and climate. In milder winter climates, leeks can be overwintered in the garden for spring harvest.
- Some varieties such as ‘Winter Giant’ and ‘Tadorna Blue’ are bred for overwintering. Temperatures as low as 20°F (-6°C) will not harm these varieties. If you leave leeks in the ground for winter harvest, hill up the soil around the plants and cover them with a heavy layer of mulch until you need them.
- Non-hardy leeks ready in 60 to 90 days will be milder flavored than long-growing, hardy varieties. Harvest non-hardy varieties in the summer and fall before the first frost.
How to Harvest Leeks
- Digging leeks is easier than pulling. Leeks have a large root system.
- Use a hand fork or garden fork to loosen the soil before lifting leeks.
- Where the soil is loose, you can harvest leeks by hand by gently twisting and pulling them from the soil.
How to Store Leeks
- Give harvested leeks a shake and brush off as much soil as possible then rinse the plant thoroughly.
- Leeks are the most flavorful used fresh.
- Store leeks wrapped in a damp paper towel in a perforated plastic bag in the refrigerator for 7 to 10 days. Smaller leeks store better than larger leeks. Trim the roots and wash the leaves and stem before refrigerating.
- Leeks store best at 32°F (0°C) and 95 to 100 percent relative humidity. Yellowing and decay develop rapidly at warmer storage temperatures. High relative humidity is essential to prevent wilting.
- Trim the leaves and slice leeks in half lengthwise immediately before use and rinse out any remaining soil that is often caught between the tight leaves.
More tips: How to Grow Leeks.