Leeks are grown for their thick, juicy stems. They are a mild-flavored alternative to the onion.
Leeks require a long growing season—up to 170 days. They grow best in cool, mild weather.
There are two types of leeks: short-season and long-season.
- Long-season leeks have thick, cylindrical stems. They take about 170 days to reach harvest. Long-season leeks are harvested late summer through the winter.
- Short-season leeks have thin stems. They mature in about 120 days. Short-season leeks are harvested during the summer. They are less hardy than long-season leeks. Short-season leeks do not store as well as long-season leeks.
- Grow leeks in full sun. Leeks will tolerate partial shade.
- Leeks grow best in well-drained soil rich in organic matter. Add a couple of inches of aged compost or commercial organic planting mix to the planting bed in spring ahead of planting. Turn the soil to 12 inches deep.
- A soil pH of 6.0 to 6.8 is best for leeks.
- Grow leeks where legumes have recently grown. They will benefit from nitrogen in the soil.
- Leeks are often sown or transplanted into trenches. Trench-planting is a way to blanch the stems making them more tender and flavorful.
- Prepare trenches 6 to 8 inches (15-20cm) deep and 4 to 6 inches (10-15cm) wide. Seedlings will be transplanted to the bottom of the trench. As plants grow backfill soil in around the plants until the trench is eventually filled.
- Leeks can be planted in soil level beds. Mound up surrounding soil or mulch to blanch leeks in soil-level beds.
- The stems of leeks also can be blanched by wrapping paper or plastic tubes around the stems.