Leeks are the quiet workhorse of the Zone 7 winter garden: sown in winter, harvested from autumn into the cold months, and sweeter for a touch of frost. This guide covers when to plant leeks zone 7 in detail: the sowing, transplanting and harvest windows for USDA Zone 7, plus spacing, soil, water, companions, pests and storage — all based on USDA zone averages and standard published crop ranges.
Zone 7 covers areas with average annual minimum temperatures of 0 to 10°F. The average last spring frost falls in the Mar 15–Apr 1 range and the average first autumn frost in the Nov 1–15 range. These are USDA zone averages, not exact dates for any one garden — check your local extension service and the forecast before planting tender crops outside. The frost-free season runs roughly seven months, from late March into early November,
When to plant leeks in Zone 7
Start leeks indoors in January or February, 10–12 weeks before the last frost, in deep modules or trays. Alternatively, sow directly in a nursery bed in March to April. Leeks need a long season — 90–120 days to maturity — so the early start is what makes the difference between fat stems and pencil-thin ones.
The table below puts the whole season on one page. All dates are ranges worked back from the Zone 7 frost averages (Mar 15–Apr 1 last frost, Nov 1–15 first frost) and the crop's published days to maturity (90–120 days). Use the frost date calculator to check the averages for your own area, and confirm them with your local extension service.
| Stage | Zone 7 window | Notes |
|---|---|---|
| Start indoors | Jan–Feb, 10–12 weeks before the last frost | Germination takes 7–14 days |
| Direct sow outdoors | Mar–Apr, in a nursery bed | Sow into moist, prepared soil |
| Transplant outdoors | Apr–May, into deep holes | Harden seedlings off first |
| First harvest | Sep–Dec, 90–120 days after sowing; stand through light frosts | 90–120 days to maturity |
| Autumn / second sowing | Sow in June for winter leeks | Count back from the first frost |
Starting and planting
Transplant in April or May, when seedlings are about as thick as a pencil. Dib a deep hole, drop the seedling in, and water it in — do not fill the hole with soil; it fills naturally and blanches the stem white as it grows. Space plants 6–8 inches apart in rows about a foot apart, in rich, moisture-holding soil.
Before sowing, fork the bed over, remove weeds and stones, and dig in well-rotted compost. Leeks grows best at a soil pH of 6.0–7.0 — test your soil through your local extension service before amending it.
Spacing, sun and soil
Space plants 6–8 inches apart. Crowded plants compete for light, water and nutrients, stay small, and invite disease through poor airflow, so thin seedlings to the final spacing once they are established.
This crop needs full sun — at least six hours of direct sun a day, and more is better. In Zone 7, a south-facing bed or an open spot away from trees and fences gives the strongest growth and the best flavour.
Soil should be deep, fertile and free-draining, with a pH of 6.0–7.0. Heavy clay improves with compost and organic matter, and raised beds help where drainage is poor.
Watering
Water needs are moderate: aim for steady, even moisture rather than feast-and-famine watering. About an inch of water a week from rain or irrigation is a useful guide in most Zone 7 summers, more in hot, dry spells. Water at the base of the plant in the morning, mulch to hold moisture, and avoid wetting the leaves, which invites disease.
Companion planting
Good companions for leeks include marigolds, basil, onions, lettuce. Planting companions nearby can help with pest confusion, pollination and making the most of bed space — marigolds, for example, are a classic companion across the vegetable garden. The companion planting finder can suggest combinations for your whole bed. Avoid planting leeks where others of the same family (Amaryllidaceae) grew last year: rotate crops each season to reduce soil-borne disease and pest build-up.
Common pests and problems
Watch for aphids, slugs, cutworms. - Aphids — inspect weekly; hand-pick or wash off with water, and encourage natural predators.
- Slugs — inspect weekly; hand-pick or wash off with water, and encourage natural predators.
- Cutworms — inspect weekly; hand-pick or wash off with water, and encourage natural predators.
Beyond pests, the main problems are weather-related: a late frost after transplanting, drought at a critical stage, or waterlogged soil after heavy rain. Cover tender plants with frost cloth if a late frost threatens, and mulch to even out soil moisture.
Harvest and storage
Harvest from September onwards, digging leeks as needed through autumn and into winter — they stand happily through light frosts and taste better for it. Lift with a fork to avoid snapping the stems, and earth up the stems through the season for longer white shanks.
Leeks keep for several weeks in the fridge, and in the ground under mulch they store themselves through winter in most of Zone 7. Trimmed and chopped, they also freeze well for soups and stews.
The classic Zone 7 mistake with leeks is planting them too shallow. Short, green, onion-like leeks are almost always a sign of shallow planting — dib deep holes and earth up through the season.
Frequently asked questions
When should I plant leeks in Zone 7?
Start leeks indoors in January or February, 10–12 weeks before the last frost, in deep modules or trays. Work from the table above, using the average last frost (Mar 15–Apr 1) and first frost (Nov 1–15), with 90–120 days to maturity. These are USDA zone averages, not exact dates for any one garden — check your local extension service and the forecast before planting tender crops outside.
How much sun does leeks need in Zone 7?
Full Sun — at least six hours of direct sun a day where possible. Give it the sunniest spot you have.
What soil pH does leeks prefer?
A pH of 6.0–7.0. Test your soil before amending it, and add compost to improve structure whatever the pH. Your local extension service can test a sample and recommend amendments.
What pests attack leeks in Zone 7?
The most common are aphids, slugs, cutworms. Inspect plants weekly, hand-pick larger pests, wash small ones off with water, and keep the bed clean and well-spaced so air circulates.
How do I store leeks after harvest?
Leeks keep for several weeks in the fridge, and in the ground under mulch they store themselves through winter in most of Zone 7. Trimmed and chopped, they also freeze well for soups and stews.
See the Zone 7 March planting guide for what else to sow and plant in the same month, browse the full planting calendar, and try the Seed Starting Calculator to plan your dates. For a related crop, see when to plant celery in Zone 7.