Leek Seeds - American Flag - Allium ampeloprasum

2, 3, 4, 5, 6, 7, 8, 9, 10, 11

USDA Zones 2-11 - Leeks are a highly adaptable cool-season vegetable grown as an annual. Success is entirely dependent on timing the planting for your specific climate to avoid summer heat during the plant's mature stage.

Best Performance in Zones 4-8 - In these temperate climates, leeks thrive. They are typically started in spring for a fantastic fall and early winter harvest, or planted in late summer in milder zones (7-8) to overwinter for a spring harvest.

Northern Zones (2-5) - Start seeds indoors very early, about 8-12 weeks before your last frost date. Transplant outdoors in spring for a harvest in the fall. The long, cool days produce excellent, sweet leeks.

Hot Climate Zones (8-11) - Do not plant in spring for a summer harvest. Leeks must be grown through the cool season. The correct method is to start seeds in early summer (May-July) and transplant them into the garden in the early fall. This allows them to mature during the mild fall, winter, and early spring months.

Soil Temperature - Seeds germinate well in cool to moderate soil, with an ideal temperature range between 60-75 degrees F.

Growing Season - This is a long-season crop. It requires 100-130 days from the time of transplanting to produce thick, mature shanks. Total time from sowing seed to harvest can be 5-6 months.

Learn more about USDA Hardiness Zones here

When to Sow:

For Fall/Winter Harvest (Zones 2-7): Start seeds indoors 8-12 weeks before your last spring frost.

For Winter/Spring Harvest (Zones 7-11): Start seeds indoors in late spring or early summer to be transplanted into the garden in early fall.

Starting Seeds Indoors:

Sow Depth: Plant seeds 1/4 to 1/2 inch deep in a deep seed tray or 4-inch pots to allow for good root growth.

Maintain Moisture: Keep the soil consistently moist and at a temperature of 60-75 degrees F. Germination takes 7-14 days.

Give Them a "Haircut": Once seedlings reach 3-4 inches in height, use scissors to trim them back to about 2 inches. Repeat this process every couple of weeks. This encourages the seedlings to grow thicker and stronger rather than tall and spindly.

Transplanting - The Trench Method:
This method is the key to producing long, white, blanched shanks.

Timing: Transplant your seedlings into the garden when they are about the thickness of a pencil.

Dig a Trench: In a prepared garden bed, dig a trench about 6-8 inches deep and 6 inches wide.

Plant: Place the leek seedlings at the bottom of the trench, spacing them about 6 inches apart.

Backfill Lightly: Gently backfill the trench with just enough soil to cover the roots (about 1-2 inches). Do not fill the trench completely.

Growing On & Hilling:

Sunlight: Leeks need full sun, which is at least 6 hours of direct sunlight per day.

Soil: Plant in loose, fertile, well-drained soil amended with plenty of compost.

Watering: Provide consistent and even moisture, about 1 inch per week, for the best growth.

Hilling for Blanching: As the leek plants grow taller, gradually fill the trench with soil every few weeks. This process is called "hilling." It shields the base of the plant from the sun, keeping it tender and white. Continue hilling until the soil is level with the surrounding garden, or even slightly mounded around the base of the plants.

Harvesting:
You can begin harvesting leeks when their shanks are about 1 inch in diameter. They do not all need to be harvested at once. In climates where the ground doesn't freeze solid (Zones 6+), they can be left in the garden and harvested as needed throughout the winter. To harvest, use a garden fork to loosen the soil around the base, then gently pull the leek from the ground.