Leek in Zone 5a & 5b
Allium ampeloprasum
Yes, leek grows in zones 5a and 5b. Start seeds indoors Mar 1–Mar 8 and plant out Apr 19–Apr 26.
When to plant leek in zone 5b
Zones 5a and 5b share the same average frost dates, so this page covers both.
Method: Start indoors: Start indoors from seed, then transplant outside. It needs a head start most zones can't give it by direct-sowing alone.
| Start indoors | Mar 1–Mar 8 |
|---|---|
| Direct sow / transplant outside | Apr 19–Apr 26 |
| Estimated harvest | Aug 7–Aug 14 (~110 days after transplanting) |
Spacing: 9 per square foot (square-foot-gardening spacing). Mature height: 1-2 ft.
Plant alongside it in zone 5b
These go outside within two weeks of leek in zone 5b, so one planting day can cover them.
- OnionApr 19–Apr 26
- RadishApr 12–Apr 19
- CabbageApr 26–May 3
- LettuceApr 26–May 3
- BeetApr 19–Apr 26
- Broccoli Rabe (Raab)Apr 19–Apr 26
Leeks take their time, 110 days from seed to harvest, but they ask for very little in return once they're in the ground. If you've grown onions or garlic, leeks are the same family playing a longer, more patient game.
How leek fits zone 5's season
Zone 5b's frost-free window runs about 148 days, from May 10 to October 5. Leek needs about 110 days from transplant to first harvest.
Leek planting windows in every zone
Zone 5b is highlighted. Useful for comparing against a neighbouring zone, or for a garden somewhere else.
| Zone | Start indoors | Sow or plant out | Harvest |
|---|---|---|---|
| 3a & 3b | Mar 21–Mar 28 | May 9–May 16 | Aug 27–Sep 3 |
| 4a & 4b | Mar 6–Mar 13 | Apr 24–May 1 | Aug 12–Aug 19 |
| 5a & 5b (your zone) | Mar 1–Mar 8 | Apr 19–Apr 26 | Aug 7–Aug 14 |
| 6a & 6b | Feb 14–Feb 21 | Apr 4–Apr 11 | Jul 23–Jul 30 |
| 7a & 7b | Jan 30–Feb 6 | Mar 20–Mar 27 | Jul 8–Jul 15 |
| 8a & 8b | Jan 14–Jan 21 | Mar 4–Mar 11 | Jun 22–Jun 29 |
| 9a & 9b | Dec 7–Dec 14 | Jan 25–Feb 1 | May 15–May 22 |
Harvest dates are about 110 days after the sow or plant-out date, not after starting seeds indoors.
Good companions
- Carrot: Same allium/carrot pest-masking effect measured for onion and carrot (Uvah & Coaker 1984): a real, peer-reviewed field study, not folklore.
Where to buy leek seeds
True Leaf Market · Burpee · High Mowing Organic Seeds (each supplier's leek seeds)
Varieties we recommend, and where to get them:
- Lancelot: Cornell's Vegetable Varieties for Gardeners database rates it 5 stars, an early-season hybrid at 90-100 days with a mild flavor and thick interior that resists bolting, a useful trait if your spring warms up fast. Buy: High Mowing Organic Seeds Full notes
- American Flag: Cornell's database has it tied for the top rating among leeks, a main-season type at 130 days with a 15-18 inch snowy white shaft, longer than Lancelot's. Buy: True Leaf Market Full notes
See why we recommend these suppliers →
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See it growing
Search YouTube for "growing leek" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
← Back to the full zone 5b calendar · Plan your beds in the Garden Designer →
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Growing Leek in USDA zone 5b: when to start seeds indoors, when to direct-sow, and when to expect a harvest.
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