To grow green onions, sow seed 1/4 to 1/2 inch deep about 4 to 6 weeks before your last spring frost, or tuck rooted grocery-store bases into soil 1 inch deep. Space them 1 to 2 inches apart, give them 6 hours of sun and about 1 inch of water a week. Seed-grown scallions are ready in about 60 to 70 days.
Green onions are one of the few crops that fit almost anywhere: a 6 inch deep window box, a gap at the front of a bed or a pot on the kitchen steps. Which also makes them easy to forget about. Most disappointments come down to thin, floppy stems, yellow tips or a sudden crop of tough flower stalks.
The fix is mostly timing. Sow a little at a time, keep the shallow roots evenly moist and pick before the plants get old. Do that and even a small patch can keep you in scallions for months.
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12 ways to grow green onions from planting to harvest
These aren’t in season order. Start with whichever one matches the problem you have now.
1. Watch the first stress signal in green onions
The first warning is usually yellow or brown leaf tips. Green onion roots sit in the top 3 to 4 inches of soil, so they feel a dry spell before most crops. Check the soil 1 inch down; if it is dry, water deeply.
Silvery streaks or speckles along the leaves point to onion thrips, which build up in hot, dry weather. A strong spray of water every few days and steady watering usually keeps them in check.
2. Harvest green onions at the useful stage
Start picking when stems are about pencil thick and 8 to 12 inches tall, roughly 60 to 70 days from seed. Pull every second plant in a row to thin it, which gives the rest room to thicken.
For a cut-and-come-again patch, snip leaves about 1 to 2 inches above the soil instead of pulling. The plant regrows in 2 to 3 weeks, and most clumps handle 2 or 3 cuts before they weaken.
3. Resow green onions only when timing fits
Sow a short row or a 12 inch pot every 3 to 4 weeks from early spring to early summer, then again in late summer for fall. You get a steady trickle instead of a glut you can’t use.
Pause in the hottest weeks. Seed germinates poorly when soil is above about 85°F, and seedlings that come up in heat often stay thin.
4. Keep developing green onions off wet surfaces
Shallow onion roots rot in soil that stays wet, and the base of the stem can turn soft and slimy. Grow them in a raised bed, a window box or a pot with drainage holes, never in a spot where water stands after rain.
Keep mulch about 1 inch away from the stems. A thin layer of straw between rows holds moisture, but piled against the necks it keeps them damp.
5. Protect green onions from the site’s strongest exposure
Light frost doesn’t bother green onions much. Summer heat does. Above about 85°F growth slows and leaves turn tough and strong tasting, so in hot regions a spot with morning sun and afternoon shade works better.
On a windy balcony, low containers help, since tall leaves flop in strong gusts. A 6 to 8 inch deep trough set against a railing wall is steadier than a tall pot on a stand.
6. Record the variety and planting date for green onions
Write the variety, sowing date and expected harvest on a plant label for each row or pot. Bunching onions, which stay slim, and regular onions harvested young as scallions look the same at first but behave differently over time.
Record each cut as well. A note like “cut twice, regrowth slower” tells you when a clump is ready to replace with fresh seed.
7. Plan the end-of-season decision for green onions
Perennial bunching onions survive winters to about zone 5 with mulch and start growing again in early spring. Scallions grown from regular onion seed are usually treated as annuals and pulled by late fall.
When winter is near, decide what stays. Keep a few strong bunching clumps under 2 to 3 inches of straw, pull the rest before the ground freezes, and replant or compost the spent ones.
8. Give green onions enough root room
Green onions need only 6 to 8 inches of soil depth. A 24 inch long window box holds about 2 rows of 12 plants at 1 to 2 inch spacing; a 10 inch pot holds a clump of 15 to 20.
In beds, rows can sit 6 to 12 inches apart. Tight spacing gives slim scallions and wider spacing gives thicker stems. I’d let your cooking decide.
9. Place green onions in the light the crop requires
Give green onions 6 or more hours of direct sun for strong, upright stems. With 4 to 5 hours they still grow, but slowly, and the leaves tend to stay thin and lean toward the light.
A sunny kitchen windowsill can keep regrown store bases going for a few weeks, but outdoor sun gives much sturdier plants. Check your spot at 9 a.m., noon and 3 p.m. and choose the one in sun at two or three of those times.
10. Support green onions before growth accelerates
Green onions never need stakes. What helps is a bit of soil: once stems are about 6 inches tall, draw 1 to 2 inches of soil or compost up around the base.
That hilling holds the stems upright and gives you a longer white section, which many cooks prefer. Do it before the fast summer growth, while the plants are still small enough to reach between.
11. Water the green onions root zone
Aim for about 1 inch of water a week, with the top inch of soil kept lightly moist. Pots and window boxes may need water every 1 to 2 days in warm weather.
Water at the base with a narrow spout. Overhead watering splashes soil into the leaf folds and keeps the leaves wet, which encourages leaf diseases.
12. Feed green onions from crop-specific guidance
Green onions grow fast and need steady nitrogen. Work 1 to 2 inches of compost into the soil before sowing, then feed every 3 to 4 weeks during active growth with a balanced or nitrogen-leaning fertilizer at the label rate.
In containers, a liquid feed at half strength every 2 to 3 weeks works well, since frequent watering washes nutrients out. Stop feeding once you plan to let a clump rest over winter.
Match green onions to the local growing window
Green onions are a cool-season crop that tolerates frost, so the last spring frost date is your starting point. The Royal Horticultural Society’s salad onion growing guide recommends sowing little and often for a continuous supply, which suits a small space well.
In most US gardens, sow outdoors 4 to 6 weeks before your last frost, once the soil can be worked and reaches about 45 to 50°F. Seed germinates in 7 to 14 days. Fall sowings go in about 8 to 10 weeks before your first fall frost. In zones 8 to 10, green onions grow through much of the winter.
Green onions go in about the same time as other early crops. If you grow peas in a small garden, a row of scallions along the front of the bed uses space the climbing peas leave free.
Plan root room, support and mature spread
Green onions are easy to sow and then lose track of. A few lines in a notebook before the first sowing keeps the batches coming.
| What to write down | Example for one window box |
|---|---|
| Container or bed | 24 inch window box, 6 to 8 inches deep |
| Sun hours | 6 hours, morning and midday |
| Variety and type | Bunching onion, perennial |
| Spacing | 1 to 2 inches apart, 2 rows |
| Sowing dates | 5 weeks before last frost, then every 4 weeks |
| Water | When the top inch is dry |
| Harvest | Start at pencil thickness, about day 60 |
Green onions take little room as they mature, rarely spreading more than 2 to 3 inches per plant. That makes them good fillers between slower crops, as long as the taller plants do not shade them out.
Aim for a soil pH around 6.0 to 7.5. A county extension soil test usually costs $15 to $30.
Coordinate water, feeding, pollination and harvest
With roots this shallow, water and feeding go hand in hand. Fertilizer only reaches fast-growing leaves if the soil stays moist, so a drink every few days does more than an extra dose of feed.
You don’t need pollination for green onions at all. When a plant sends up a stiff, round flower stalk, that stalk turns woody. Snip it off at the base and use the leaves soon, or let one or two clumps flower for bees and seed while you harvest from others.
Plan harvests around sowing dates. Pull the oldest row first, cut regrowing clumps every 2 to 3 weeks and sow again as each row is used. Green onions also pair well with leafy crops harvested young; if you grow spinach in a small garden, both can share a bed and a watering routine.
Read green onions stress before changing the routine
Before you change anything, match what you see to a likely cause.
- Yellow tips: dry soil, heat or low nitrogen. Water first, then feed if it continues.
- Floppy, thin stems: too little sun or crowding. Thin to 2 inches and move pots into sun.
- Silver streaks: thrips. Spray with water and keep plants watered.
- Soft, rotting bases: wet soil. Improve drainage before sowing again.
- Wilting plants with damaged roots: possible onion maggots. Pull affected plants and sow the next batch in a new spot.
Onions, including green onions, are toxic to dogs and cats according to the ASPCA. Keep trimmings and pulled plants out of their reach.
FAQ
What should I know before planning green onions?
Know your last frost date, your sun hours and how much soil depth you have. Green onions need 6 hours of sun, 6 to 8 inches of moist, well-drained soil and steady water. Pick perennial bunching onions or annual scallions before buying seed.
How much space does green onions need?
Each plant needs only 1 to 2 inches of space, with rows 6 to 12 inches apart. A 24 inch window box holds about 24 plants and a 10 inch pot holds 15 to 20. Depth matters more than width: aim for at least 6 inches.
What is the simplest way to start green onions?
The quickest start is regrowing grocery store green onions: plant the white bases with roots attached 1 inch deep in a pot, water and place them in sun. New leaves appear within 1 to 2 weeks. For a longer supply, sow seed every 3 to 4 weeks.
What common mistakes should I avoid with green onions?
The usual mistakes are letting the soil dry out, sowing too thickly, harvesting too late and growing them in too little sun. Each leads to thin, tough or yellow plants. Thin to 1 to 2 inches, keep the soil moist and pick at pencil thickness.
How do I maintain green onions over time?
Water when the top inch is dry, feed every 3 to 4 weeks and snip flower stalks as they appear. Cut clumps 1 to 2 inches above soil to regrow, and replace them after 2 or 3 cuts. Sow a fresh batch regularly for a steady supply.
When should I get local or expert advice about green onions?
Contact your county extension office if plants rot or wilt across several sowings, pests return each year or leaves show spreading spots or purple lesions. They can identify onion maggots or leaf diseases and give local sowing dates.
Final thoughts
Green onions are about the easiest win a small garden has, mostly because they ask for so little room. The work is a loop: sow a little, keep the soil moist, cut or pull at pencil thickness, sow again.
This week, fill one 6 to 8 inch deep pot or window box, sow a short row and mark the next sowing date 4 weeks out on its label. Keep that pot apart from dry-loving herbs: the steps to grow thyme call for soil that dries out between waterings, which green onions do not enjoy.
Last update on 2026-10-01 / Affiliate links / Images from Amazon Product Advertising API