18 - Leeks
Varieties
- King Richard
Growing Conditions
Propagation
Life cycle
Soil block size
Light requirements and depth
Seed germination temperature
Heat mat temp
Cool germination details
Planting details
Beginning in early spring or late summer, when approx. 8″ tall and pencil-thick, transplant 6″ apart in rows at least 12″ apart in holes dibbled 6″ deep. Only 2-3″ of leaves need to extend above the soil surface. Do not firm soil – allow irrigation or rain to fill in the dibble hole.
Leeks will grow in any garden that will produce good onions. The edible portion of the leek stem should be blanched for best flavor and tenderness. When the plants are at least the width of a pencil, begin to gradually draw soil up around the base of the plant to blanch the lower stem. Avoid starting to blanch the stems too early. Otherwise, grow as you would onions.
Traditional garden wisdom recommends using a dibber to make holes 15cm (6″) deep. Transplants are then set at the bottom of the hole and the hole is left unfilled – rain will fill it in as the leek grows. To blanch further up the stem, hill soil up around the stem as the leek grows, or mulch with straw.
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However, the wise and much loved garden writer Linda Gilkeson asserts that there is no need to plant leeks into holes or trenches. She recommends transplanting the seedlings only at the depth of the soil plug they grow in. They will still produce nice, tall, blanched shanks, with no soil grains between the leaves.
In late fall, mulch around leeks as high up the stems as possible. If the forecast is for weather below -10° (14°Ï‚ cover them with a blanket or tarp.
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However, you don’t have to bury them so deep. Leeks grow just fine if only minimally buried, planted 2-3″ deep. Their stalk color will simply be light green instead of pearly white. If you desire extra-white leeks, you can always blanch them later after planting (read more below). Or, simply let them grow au natural like we usually do!
Culture and fertilization requirements
Leeks thrive in temperatures 55-75°F. They can tolerate hotter weather, though their growth rate may decline. Spring or late summer to fall in mild southern climates. Direct sow or transplant: starting leek seeds indoors to transplant later is preferable in most cases. Sow in flats in Feb.-March, 1/4″ apart, 1/4″ deep or start in plug flats, thinning to one plant per cell. Leeks are heavy feeders and require fertile soil (pH of 6.2-6.8) for best results.
Growing preferences: full sun, ample consistent water, well-draining soil, moderate nitrogen and organic matter.
In the absence of a soil test, apply 25 pounds of 5-10-10 per 1,000 square feet before planting. Leeks should be sidedressed four times throughout the growing season with 3 pounds of calcium nitrate (15.5-0-0) per 1,000 square feet. This should be done mid-November, early January, mid-February, and early March.
Harvesting details
During the growing period hill the plants with soil 2 or 3 times, higher with each hilling. This forces the leaves higher up the plant resulting in extra-long blanched stalks and a much longer edible portion. When using the “dibble method,” hilling is reduced or eliminated.
Links - Pests, Disease, General Info
Current Seed Start & Transplant Dates
Note: Seed starting and transplant dates do not always correlate one to one with dates shown below. Note correct start and expected transplant dates on the tag of the tray for seed germination. Adjust dates with plant tags on a yearly basis if necessary. 8 ounces of fertilizer is about 1 cup. Consider Sustane various NPK and Alfalfa Meal or Blood Meal for nitrogen.
| Seed Start to Transplant Days | 84 days |
| Days to Maturity after Transplant | 55 to 140 days after transplanting, depending on variety |
| Days to Maturity Total | 135 - 240 |
| Number of Plantings per Season | 1 Spring | 1 Fall |