Green onions grow reliably when sown directly in the garden four weeks before the last frost. Knowing when to plant green onions is the key to a steady harvest of crisp, mild scallions all season long. This guide covers everything from spring sowing to fall planting, so you never miss the window.
When To Plant Green Onions
Timing matters more than you think. Plant too early and cold soil can rot seeds. Plant too late and summer heat makes them bolt. The sweet spot depends on your climate and your goal—whether you want a quick spring crop or a winter stash.
Spring Planting: Start 4 Weeks Before Last Frost
Green onions are cold-hardy. Seeds germinate in soil as cool as 40°F (4°C). For most regions, direct sow seeds 4 weeks before your average last frost date. This gives them a head start without risking frost damage to young shoots.
- Check your local frost dates online or via a gardening app.
- Count backward 28 days from that date.
- Prepare beds with loose, well-draining soil.
- Sow seeds ¼ inch deep, 1 inch apart.
If you live in zones 7-10, you can plant even earlier—late winter often works. In colder zones (3-5), wait until soil is workable, not frozen.
Fall Planting: For A Winter Harvest
Many gardeners don’t realize you can plant green onions in autumn. In mild climates (zones 8-10), sow seeds 8-10 weeks before the first fall frost. They’ll grow slowly through winter and give you scallions in early spring.
For colder areas, plant in late summer (August to September) and mulch heavily. The onions will go dormant but survive under snow. They resume growth as soon as soil warms.
Succession Planting: Keep The Harvest Coming
Instead of planting once, sow a new row every 2-3 weeks. This gives you a nonstop supply from spring through fall. Stop planting about 6 weeks before your first fall frost to allow the last batch to mature.
- Mark your calendar for each sowing date.
- Use a small patch or container for each round.
- Thin seedlings to 2 inches apart for thicker stems.
- Harvest when stems are pencil-thick, usually 60-70 days from seed.
Factors That Affect Planting Time
Your exact planting date shifts based on a few things. Let’s break them down.
Your USDA Hardiness Zone
Zone 3-4: Plant in late April to early May. Soil warms slowly, so use black plastic to speed it up.
Zone 5-6: Mid-April to early May works well. You can also start seeds indoors 6 weeks before transplanting.
Zone 7-8: Early March to April. Fall planting in September gives winter scallions.
Zone 9-10: Year-round planting is possible. Avoid midsummer heat (July-August) when growth slows.
Soil Temperature
Green onion seeds germinate best at 60-75°F (15-24°C). Use a soil thermometer to check. If soil is below 40°F, wait. If above 85°F, seeds may go dormant.
To warm soil faster in spring, cover beds with row covers or clear plastic for 2 weeks before planting.
Day Length
Green onions are day-neutral, meaning they don’t depend on light hours to bulb. But they do grow faster in longer days (14+ hours). Spring planting gives you the longest growing days, so plants mature quicker.
Fall planting has shorter days, so growth is slower but the flavor is sweeter after a light frost.
How To Plant Green Onions Step By Step
Once you know when to plant, the actual process is simple. Follow these steps for success.
Prepare The Soil
Green onions prefer loose, fertile soil with a pH of 6.0-7.0. Remove rocks and weeds. Mix in 2 inches of compost or aged manure. Avoid fresh manure—it can burn roots.
Raised beds work great because soil warms faster and drains well. Containers need at least 6 inches depth.
Sow The Seeds
Make shallow furrows ¼ inch deep. Space rows 12 inches apart. Drop seeds every 1 inch, then cover lightly with soil. Water gently with a fine spray to avoid washing seeds away.
Germination takes 7-14 days. Keep soil consistently moist but not soggy.
Thin The Seedlings
When seedlings are 2 inches tall, thin them to 2 inches apart. You can eat the thinnings as microgreens. Thicker spacing gives larger scallions.
For bunching onions (multiplier types), you can leave them closer—they’ll grow in clusters.
Water And Mulch
Green onions need about 1 inch of water per week. Mulch with straw or grass clippings to retain moisture and suppress weeds. Avoid overhead watering late in the day to prevent fungal diseases.
Common Mistakes With Planting Timing
Even experienced gardeners slip up. Here are the top errors and how to avoid them.
Planting Too Early In Cold Soil
Seeds rot in cold, wet soil. If you plant before the soil reaches 40°F, germination is spotty. Wait until the ground is workable and not muddy.
Tip: Do a “soil squeeze test.” Grab a handful of soil. If it crumbles, it’s ready. If it forms a muddy ball, wait.
Planting Too Late In Hot Weather
Green onions stop growing when temps exceed 85°F. They may bolt (flower) and become tough. In hot climates, plant in early spring or fall. Provide shade cloth if a heat wave hits.
Ignoring Your Microclimate
Your garden may be warmer or cooler than the general zone. South-facing slopes warm faster. Low spots collect frost. Observe your yard for a few seasons to fine-tune your planting dates.
Growing Green Onions In Containers
Container gardening lets you control timing better. You can move pots to sun or shade as needed.
Use a pot at least 6 inches deep with drainage holes. Fill with quality potting mix. Sow seeds ¼ inch deep, 1 inch apart. Water regularly—containers dry out faster.
You can plant containers indoors year-round if you have a sunny window or grow lights. This means you can harvest green onions even in winter.
Harvesting At The Right Time
Green onions are ready when the stems are 6-8 inches tall and about ½ inch wide. You can harvest earlier for thinner scallions or later for thicker ones. Pull them by the base, or cut them 1 inch above the soil to regrow.
For continuous harvest, use the “cut and come again” method. Leave the roots and a small stub. New shoots will emerge in 2-3 weeks.
Frequently Asked Questions
Can I Plant Green Onions In Summer?
Yes, but avoid the hottest months. In zones 7-10, plant in late summer (August) for a fall harvest. In cooler zones, summer planting works if you provide shade and consistent water.
How Late Can I Plant Green Onions In Fall?
Plant 8-10 weeks before your first hard frost. In mild climates, you can plant through October. In cold zones, stop by September to allow growth before dormancy.
Do Green Onions Need Full Sun?
They grow best in full sun (6-8 hours daily). Partial shade is okay but slows growth. In hot climates, afternoon shade helps prevent bolting.
Can I Regrow Green Onions From Kitchen Scraps?
Yes. Place the white root ends in a glass of water. Change water every 2 days. After roots form, transplant to soil. This works best if you start with fresh store-bought onions.
What Is The Best Month To Plant Green Onions In Zone 6?
April is ideal for spring planting. For fall, plant in late August to early September. You can also start seeds indoors in March and transplant in April.
Final Tips For Perfect Timing
Keep a garden journal. Note your planting dates, weather, and harvest quality. Over time, you’ll learn the exact window for your location.
Don’t stress about perfection. Green onions are forgiving. Even if you plant a week late, you’ll still get a crop. The key is to start somewhere and adjust next season.
Remember: when to plant green onions is about reading your garden, not just a calendar. Watch the soil, watch the weather, and trust your instincts. Happy growing.