Leeks are excellent onion substitutes and are easy to grow! They are much milder than onions and quite sweet. Attractive blue‐green strap‐like leaves emerge from the flavorful white stem. They need a long growing season, and are very cold hardy. Leeks can even be grown in containers, yielding slightly smaller plants.
Leeks require full sun (at least six hours of direct sun). They thrive in rich, well drained, loose soil. Spread 2‐ 3” of composted manure over the bed and work it into the soil before planting. Also, add a granular all purpose fertilizer and lime to each planting trench.
Start seeds indoors January to mid‐March, 8‐10 weeks before last frost. Follow planting depth and spacing guidelines on seed packet. Thin seedlings 1⁄2” apart and trim to 3” tall for thicker plants. Transplant seedlings into the garden April through July. Plant leeks into the bottom of a 5‐7” deep and wide trench. Space plants 4‐5” apart. Begin blanching as plants grow and thicken by piling soil or straw around the leeks inside the trench. This practice keeps the bottom of the leeks white and tender.
Leeks can also be directly seeded into the garden mid‐April through May. Sow seeds 1⁄4 ‐ 1⁄2” deep in rows 12‐18” apart. Thin seedlings to 4‐5” apart. This crop will mature in time for fall and winter harvest.
How much water your plants will require depends on the soil and weather. Leeks enjoy lots of water. Water beds when the top 2‐3” of the soil is dry. Drip irrigation is the best way to provide even moisture while having fewer disease issues.
Mix all‐purpose fertilizer into the bottom of each trench at planting time. Side dress every month with a high nitrogen fertilizer until leeks reach mature size.
Once leeks reach 1⁄2” in diameter they are harvestable. Use a garden fork to loosen the soil around the plants. Leeks can stay in the ground well into winter in our climate. If temperatures drop below 20°F mulch with straw to extend harvest season. Harvested leeks will store with refrigeration for about a month.
Good gardening practices such as crop rotation, drip irrigation, proper planting time, floating row covers and removal of entire plants when harvest is done all help prevent many pests and diseases.