Most of the garden is winding down this week. Tomatoes are pulled, the last squash is curing, and the jack-o'-lanterns are on the porch. The onion family is different. Bunching onions and leeks are some of the toughest plants you can grow, and if you plan for them now you can have something green and oniony to cut most of the winter, and an early start in spring.
Here's what to do with them this fall, depending on where you garden.
Why bunching onions are the winter onion to grow
Bulb onions depend on day length and take most of a season to size up. Bunching onions (Allium fistulosum) don't. They never form a real bulb. They just keep making slender white stalks and hollow green tops, and they're a hardy perennial in most of the country. Established clumps can ride out hard freezes, die back a little, and push new green growth as soon as the soil starts to warm in late winter. They're often the first fresh thing you'll pick in the year.
Tokyo Long White bunching onion is a classic Japanese type with long, tender white shanks and a mild flavor. Use it raw on tacos and baked potatoes, or chop a big handful into soups and stir-fries. Pull it young as scallions, or let it grow into thick, leek-like stalks.
What to do this week, by zone
Zones 7–10: sow outdoors now
If you garden in the South, the Gulf Coast, the low desert, or coastal California, late October and November is a great time to direct sow bunching onions. Cool weather suits them, and they'll grow slowly but steadily through winter. You should be cutting green onions by late winter or early spring.
- Sow seed about 1/4 inch deep in loose, fertile soil, in rows or small clumps about 1/2 inch apart.
- Keep the bed evenly moist until they come up. In cooler soil that can take two weeks or more, so be patient.
- Thin to about an inch apart for scallions, or 2–3 inches if you want thicker stalks. Eat the thinnings.
Zones 5–6: use cover or containers
By now, seed sown in open ground probably won't get big enough to settle in before the ground freezes. You still have two good options:
- Cold frame or low tunnel: Sow in a protected bed now. The seedlings will stay small over winter, then take off early in spring well ahead of anything sown in March.
- Pots outdoors, then inside: Sow a deep container and bring it to a bright windowsill or unheated sunroom when hard freezes arrive.
Already have an established clump? Leave it in the ground, cut the tops back, and mulch around it with a few inches of straw or shredded leaves.
Zones 3–4: grow them on a windowsill
Up north, bunching onions are an easy indoor crop. Fill a pot at least 6 inches deep with potting mix, sprinkle the seed thickly over the surface, cover with 1/4 inch of mix, and keep it somewhere warm until the seedlings come up. Then move it to your sunniest window. You can start snipping in about 8–10 weeks. Cut the tops an inch or so above the soil and they'll grow back several times. Keep some seed for outdoor sowing as soon as you can work the soil in spring.
Leeks: the slow, sweet, cold-hardy one
Leeks take patience. They're a long-season crop, usually started indoors in late winter and harvested the following fall. Their payoff is that they handle cold very well. American Flag leek is a dependable heirloom known for its hardiness, with thick white shanks that turn sweeter as the weather cools.
If you have leeks in the ground now: In mild-winter areas (roughly zone 7 and warmer), you can usually leave them in the bed and dig them as you need them all winter. In zones 5–6, hill soil up around the stems and pile on a thick layer of straw or leaves so you can keep harvesting into early winter. Pull the rest before the ground freezes solid. Trimmed leeks keep for weeks in the fridge, or chop them and freeze them for soup.
If you're planning ahead: Put "start leeks" on your calendar for about 10–12 weeks before your last spring frost. For much of the country that's January or February. Leeks sown indoors then, and set out in spring, will be ready by next fall. Gardeners in zones 8–10 can also sow leeks in fall for a spring harvest.
A perennial bonus: garlic chives
If you like onions you don't have to replant, add garlic chives to your spring list. They're a hardy perennial with flat leaves that taste like mild garlic, and they bloom in late summer with white flowers the pollinators love. They die back in a hard freeze and come back every spring. Start them indoors in late winter or sow them outdoors once the soil warms. If you're already growing a pot of bunching onions on the windowsill, garlic chives grow happily right next to them.
Quick tips for onion-family seed
- Use fresh seed. Onion and leek seed doesn't stay viable for long. Buy what you'll sow this season and next, and store it cool and dry.
- Don't let seedlings dry out. They have small, shallow roots and stall fast if the soil goes dry.
- Feed lightly and keep weeds down. Alliums have thin leaves and can't compete with weeds for light.
- Harvest often. Bunching onions produce more when you keep cutting them.
Even a short row or a single pot of Tokyo Long White means you can walk out in January and cut fresh green onions instead of buying a limp bunch at the store. Happy planting!