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When to plant green onions

Onion family, Allium fistulosum

Spacing
2″ apart
Per sq ft
16
To harvest
60–70 days
Frost
Hardy

Companion plants for green onions

What to grow next to green onions, what to keep away, and what is only tradition. Every pairing says how strong the evidence is.

Tradition only 2

On many charts, with little or no evidence.

  • Lettuce Tradition Said to help Said to keep aphids off lettuce. Aphid repellence by scent has not been shown.

    Lettuce guide

  • Red leaf lettuce Tradition Said to help Said to keep aphids off lettuce. Aphid repellence by scent has not been shown.

    Red leaf lettuce guide

Studied Field or lab research shows an effect, at least under some conditions.
Mixed Some studies find an effect, others don’t, or it only works in a narrow way.
Practical Explained by light, space, timing, support or a shared pest or disease.
Tradition Widely repeated, but with little or no evidence behind it.

See every pairing side by side in the companion planting chart, or try them in a bed with the garden planner.

When to plant green onions by city

Sow green onions outdoors from 4 weeks before to 4 weeks after your last frost. For a fall crop, sow 8–10 weeks before your first fall frost. Here is what that means for 2027 in cities across the US, using each city’s average frost dates (NOAA 1991–2020). Pick the city with the climate most like yours, or enter your ZIP code above.

City Last frost Sow outdoors Fall crop
Seattle, WA (9a) Mar 13 Feb 13 – Apr 10 Sep 8–22
Portland, OR (8b) Feb 25 Jan 28 – Mar 25 Sep 22 – Oct 6
Sacramento, CA (9b) Jan 12 Dec 15 – Feb 9 Oct 7–21
Phoenix, AZ (10a) Jan 5 Dec 8 – Feb 2 Oct 25 – Nov 8
Salt Lake City, UT (7b) Mar 31 Mar 3 – Apr 28 Aug 30 – Sep 13
Denver, CO (6a) Apr 30 Apr 2 – May 28 Aug 3–17
Dallas, TX (8b) Mar 2 Feb 2 – Mar 30 Sep 20 – Oct 4
Minneapolis, MN (5a) Apr 23 Mar 26 – May 21 Aug 7–21
Kansas City, MO (6b) Apr 4 Mar 7 – May 2 Aug 24 – Sep 7
Chicago, IL (6b) Apr 10 Mar 13 – May 8 Aug 27 – Sep 10
Columbus, OH (6b) Apr 20 Mar 23 – May 18 Aug 15–29
Nashville, TN (7b) Apr 1 Mar 4 – Apr 29 Aug 22 – Sep 5
Atlanta, GA (8a) Mar 24 Feb 24 – Apr 21 Aug 30 – Sep 13
Raleigh, NC (8a) Mar 28 Feb 28 – Apr 25 Aug 30 – Sep 13
Philadelphia, PA (7b) Mar 30 Mar 2 – Apr 27 Sep 8–22
Boston, MA (7a) Apr 4 Mar 7 – May 2 Aug 31 – Sep 14

In frost-free parts of Florida, southern California and the Gulf Coast, timing is about heat instead: grow green onions from fall through winter.

Green onion spacing

In a square-foot bed, plant 16 per square foot. In traditional rows, space plants about 2 inches apart with 12 inches between rows.

Tuck them into gaps between slower crops.

One square foot planted with green onions, as drawn in the planner.

How to grow green onions

Green onions, also called bunching or Welsh onions, never form a bulb. They are quick from seed, take very little room and are easy to tuck between slower crops. Bunching types are hardy and can overwinter in many areas.

Sun and soil

Full sun to part shade, in fertile, well-drained soil with a pH of about 6.0–7.0. Keep soil evenly moist; the shallow roots dry out quickly.

Planting

  1. Sow ¼–½ inch deep from 4 weeks before to 4 weeks after the last frost, once soil is at least 45°F.
  2. Thin to about 2 inches apart in rows 12 inches apart, or grow in a dense band and harvest by thinning.
  3. Sow a short row every 3–4 weeks in spring for a steady supply.
  4. Sow again 8–10 weeks before the first fall frost for fall and overwintered onions.

Care

  • Weed early and often; small seedlings are easily smothered.
  • Water regularly and mulch lightly once plants are a few inches tall.
  • A light side-dressing of nitrogen keeps leaves growing.

Harvest

Start harvesting when plants are 6–8 inches tall. Pull whole plants, or cut leaves an inch or two above the soil and let them regrow several times. Bunching onions left in place divide and multiply into clumps.

Common problems

  • Thrips: Silvery streaks on leaves. Spray plants with water and keep surrounding weeds down.
  • Onion maggot: Rotate where alliums grow and use row cover in spring.
  • Weed competition: Thin, slow seedlings. Hand-weed early and mulch between rows.

Varieties to try

  • 'Evergreen Hardy White' — very cold hardy, can overwinter
  • 'Ishikura' — long, straight white shanks
  • 'He-Shi-Ko' — fine-leaved bunching onion

Crop rotation

Green onions belong to the onion family (Amaryllidaceae). Onion maggot and white rot persist. Rotate for 3–4 years. Relatives that count as the same family for rotation: onion, garlic, leek, chives.

Frequently asked questions

When should I plant green onions?
Sow green onions outdoors from 4 weeks before to 4 weeks after your last frost. For a fall crop, sow 8–10 weeks before your first fall frost. Type your ZIP code above for exact dates, or see the city table.
How far apart should I plant green onions?
In rows, space green onions about 2 inches apart with rows 12 inches apart. In a square-foot bed, plant 16 per square foot.
How long do green onions take to grow?
About 60–70 days from sowing to first harvest, depending on the variety and the weather.
Can green onions handle frost?
Yes. Green onions handle frost well and are planted before the last frost in spring and again for a fall harvest.

Sources

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When to plant

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