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Vegetable Crop Calendars (A–C)Leek Planting Calendar: Long-Season Crop
Leeks are slow, steady growers that finish in the cool end of the year, so the calendar begins with seed trays in late winter.
Key points
- Leeks need a long season, so start seed early indoors.
- Count back from target transplant date.
- Hill soil in stages for long white shafts.
- Many varieties tolerate frost.
- Rotate away from other alliums.
Why do leeks need such a long season?
Leeks grow slowly, especially in the first weeks, and the part we eat is a long blanched shaft that takes time to build. Most varieties need many weeks from transplant to harvest, with a long period of seedling growth before that. Check the days to maturity on your seed packet and treat it as a minimum.
Varieties differ in cold hardiness. Some are bred for fall harvest and others for overwintering, so choose by when you want to harvest.
Treat the first year as a trial. Even experienced growers adjust their leek calendars for their own conditions, and a small planting teaches you which varieties and dates work in your garden.
When do you start seed?
Most gardeners start seed indoors many weeks before the last spring frost, then transplant seedlings once they are about pencil thickness. Your state guide gives the number of weeks to start seed before transplanting, so use that figure.
Seed germinates slowly. Keep the medium evenly moist and give seedlings strong light. Some gardeners trim tops to keep them sturdy, a practice described in several guides.
Count backward from your target transplant date. For example, if you want to plant out in mid-spring, you would start seed well before that date, in late winter. That is an illustration of the method, so confirm with local guidance. If a few seedlings grow thin and weak, discard them and keep the sturdy ones. Strong transplants are worth the extra culling.
- Pick your target transplant date.
- Count back using your guide's seedling weeks.
- Keep seedlings in bright light.
- Harden off before planting out.
How do you transplant for long white shafts?
Leeks are often set into a trench or deep holes, then gradually filled in or hilled as they grow. Soil that covers the lower stem excludes light and creates the long, white shaft. Take care to keep soil from falling into the center of the plant.
Space plants according to your guide, and water them in. Roots are shallow, so keep the bed weeded gently.
A dibble or a broom handle makes planting holes quickly. Drop a seedling into each hole and water it in, letting the soil settle around the roots rather than packing it down. A common mistake is burying the growing point. Keep the fan of leaves above the soil line, and fill the trench gradually so that only the lower portion of the shaft is covered at any time.
What do leeks need while they grow?
Leeks want fertile, well-drained soil and steady moisture. A soil test shows pH and nutrient status, and your extension office can interpret it. Nutrient management rules vary by state, so follow local recommendations.
Because the crop stays in the ground so long, mulch helps hold moisture and suppress weeds. Hill soil in stages as plants grow, rather than all at once.
Weeds are a particular problem because leeks are slow starters. A mulch of straw or leaves keeps them in check, and hand weeding is best near the shafts. A soil test is especially useful for a crop that stays in the bed for most of a season, because it shows whether early fertility will last.
When and how do you harvest?
Harvest when shafts reach a useful size, which can be well before full size if you like small leeks. Many types tolerate frost, and some overwinter in mild regions with mulch. A hard freeze can damage plants in colder areas, so pull before the ground freezes solid or cover them.
Use a fork to loosen soil and lift plants without snapping them. Trim roots and tops.
For preserving leeks, use only tested procedures from the National Center for Home Food Preservation. Pulled leeks store well in a cool place or can stay in the ground in mild climates. Many guides suggest mulching heavily for winter harvest.
What problems affect leeks?
Onion thrips, leek moth in some regions, and rust and other leaf diseases are common concerns. Rotation away from other alliums lowers disease and pest pressure. Row cover can help where leek moth is present.
If a pesticide is ever considered, read the label, observe the pre-harvest interval, protect pollinators and check licensing rules. Ask your extension office what is active in your area.
Remove old leaves and debris at season's end, and avoid following leeks with onions or garlic in the same bed for a few seasons.
Sources and further reading
Last reviewed: November 2026. Educational information, ranges only. Confirm timing with your county extension office.