Scallions are the fastest allium you can grow — 60–70 days from seed to table — and they are so easy that indoor starting is optional, not essential. But a tray started indoors gives you the first scallions of spring weeks ahead of the outdoor sowing.
Scallions belong to the Amaryllidaceae family, need full sun, and take 60–70 days to mature, with seed germinating in 7–14 days. That combination — a moderate season and fairly quick germination — shapes every decision in this guide, from when you sow to whether indoor starting is even worth it. Scallions are usually direct-sown: the seed is cheap, germination takes only 7–14 days, and the plants are harvested young, so there is no long season to protect. Indoor starting is a shortcut to an early crop, not a requirement. If you do start them inside, sow thickly and transplant in clumps — scallions are perfectly happy growing in bunches.
Scallions at a glance
| Growing factor | What scallions need |
|---|---|
| Days to germination | 7–14 |
| Sowing method | direct sow |
| Days to maturity | 60–70 |
| Soil pH | 6.0–7.0 |
| Spacing | 2–3 inches |
| Sun | full sun |
| Cold tolerance | hardy |
| Water needs | moderate |
| Family | Amaryllidaceae |
When to start scallions seeds indoors
Direct-sow scallions outdoors from 2–3 weeks before your last frost in Zones 3–6, and sow again every few weeks for a continuous supply. In Zones 7–9, sow through spring and autumn. In Zones 10–13, sow through the cool season. For an early crop, start a tray indoors 4–6 weeks before your last frost.
Timing in brief: direct sow from 2–3 weeks before your last frost; indoors 4–6 weeks before, only if you want an early crop. Work backwards from your last frost date using our seed-starting calculator and the frost-date calculator, and confirm the timing with your local extension service. Zones 11–13 are frost-free, so never plan around a frost date there — the calendar in those zones is about heat and rain instead. If you are unsure of your zone, the hardiness-zone finder will confirm it.
What you need
- Fresh scallions seed — check the packet date, and test old seed before you rely on it
- Seed trays or cells, plus peat pots or soil blocks if you are starting a crop that dislikes root disturbance
- Fine, sterile seed-starting mix — not garden soil, which is too heavy and carries disease
- A spray bottle or a tray for bottom watering
- Labels and a marker — scallions seedlings all look alike at first
- A grow light, or the brightest windowsill you have
- A heat mat, if you are starting a warmth-loving crop or your room runs cool
- Clean water, and a small fan for air circulation once seedlings emerge
Keep the seed packet as your reference for variety, sowing depth, and days to maturity. Wash reused trays in hot soapy water first — old compost is where damping-off fungi live.
Step by step: starting scallions seeds indoors
Sow scallion seed 1/4 inch deep, thickly, in trays or directly in the bed. Germination takes 7–14 days. If starting indoors, transplant the seedlings in clumps of five or six — do not separate them one by one. Thin outdoor rows to 2–3 inches apart, or leave them thick for slim scallions.
- Fill your containers. Fill trays, cells, or peat pots with moist seed-starting mix, damp like a wrung-out sponge. Water dry mix before you sow, not after.
- Sow at the right depth. Sow at the depth on the packet and no deeper — seed sown too deep runs out of energy before it reaches the surface.
- Label everything. Write the variety and sowing date on every tray.
- Water gently. Mist the surface or water from below so seed is not washed away. Cover the tray to hold moisture in, and remove the cover the moment seedlings appear.
- Keep it warm and bright. Seed germinates in 7–14 days in suitable conditions — check daily, and move the tray into light the moment green appears.
- Thin to the strongest. If two seedlings share a cell, snip the weaker one at soil level — pulling disturbs the roots of the one you keep.
- Pot on when ready. Move seedlings into individual pots once they have two or three true leaves, handling them by a leaf, never the stem.
- Feed lightly. Seed mix has almost no nutrients, so once seedlings have true leaves, feed at half strength with a balanced liquid feed every week or so.
For direct-sown crops, the outdoor version is simpler: sow where the plant will grow, keep the bed moist until germination, and thin to 2–3 inches apart. The soil pH for scallions should be 6.0–7.0.
Light for seedlings
Scallion seedlings need strong light to stay upright. Give them a bright spot or a grow light a few inches above the leaves — floppy seedlings are usually light-starved.
Give seedlings 14–16 hours of light a day. A south-facing windowsill can work in spring, but most seedlings do better under a grow light hung a few inches above the leaves and raised as they grow — if the light is too far away, seedlings stretch and go leggy, and leggy seedlings rarely recover. Our grow-light calculator can help with hanging height and hours. Give them a dark night too; do not leave lights on around the clock.
Watering seedlings
Keep the seedbed or tray evenly moist during the 7–14 day germination window. Scallions need moderate, steady water — they are shallow-rooted, so a dry surface checks them quickly.
Water seedlings from below whenever you can: stand the tray in a shallow dish for ten minutes, let the mix soak it up, then drain it away. Top watering washes seed around and keeps the surface wet, which invites damping off. Keep the mix evenly moist — never soggy, never dry — and check daily, because a small cell dries fast under lights and a dry spell during the 7–14-day germination window can stall the seed. Once seedlings have true leaves, let the surface dry slightly between waterings. Our watering calculator gives a starting point. Use room-temperature water — cold water shocks young roots.
Hardening off
Harden scallions off over a few days. They are hardy and tolerate cool nights well, so the move outside is gentle — just avoid putting tender indoor seedlings straight into wind and strong sun.
Hardening off means getting indoor seedlings used to the outdoors gradually, over 7–10 days. Start with a few hours in a sheltered, shady spot, then lengthen the time outside each day and introduce more sun and wind. Bring trays in at night for the first few days, especially if frost threatens. Seedlings put straight outside without hardening off wilt, scorch, or stop growing for weeks — the shock undoes all the careful indoor work.
Transplanting outdoors
Set scallion clumps 2–3 inches apart in fertile, well-drained soil in full sun. Water in and mulch lightly. Harvest by pulling whole clumps as needed, starting when stems are pencil-thick.
Scallions grow best in full sun and a soil pH of 6.0–7.0, so choose the sunniest suitable spot and test the soil before you plant. Good companions nearby include marigolds, basil, onions. Space plants 2–3 inches apart — crowding is one of the commonest causes of small harvests. Our plant-spacing calculator works out how many plants fit your bed. Plant on a cloudy day or in the evening, water in thoroughly, and mulch to hold moisture.
Common problems and fixes
| Problem | Fix |
|---|---|
| Aphids | Check plants regularly, remove by hand, and cover young plants with insect mesh. |
| Slugs | Spray off with water and encourage beneficial insects. |
| Damping off | Use fresh sterile seed mix, water from below, and give seedlings good air circulation. |
| Leggy seedlings | Move grow lights closer — a few inches above the leaves — and give 14–16 hours of light a day. |
| Seed not germinating | Check the seed is fresh and the compost is moist; scallions seed takes 7–14 days to germinate. |
Floppy seedlings
Too little light. Move lights closer and give 14–16 hours a day.
Slow germination
Cold or dry soil. Scallions germinate in 7–14 days in warm, moist conditions — keep the tray moist and warm.
Slugs on young plants
Slugs love young alliums. Use barriers and keep the bed tidy.
Frequently asked questions
Do I need to start scallions indoors?
No — scallions are usually direct-sown and take only 60–70 days to mature. Indoor starting just gives you an earlier first harvest.
Can I grow scallions in clumps?
Yes, and you should. Sow thickly and transplant in clumps of five or six; they grow happily bunched together.
How do I keep scallions coming all season?
Sow a short row every two to three weeks from spring to late summer. Each sowing takes 60–70 days, so succession sowing is the whole trick.
How long do scallions seeds take to germinate?
Scallions seed takes 7–14 days to germinate in suitable conditions. Keep the compost moist and at room temperature, and use fresh seed — old seed germinates slowly or not at all. Our germination-time calculator can help you work out the timing for your sowing.
Can I use old scallions seed?
Check it first. Seed viability falls with age and poor storage, so test a few seeds on damp kitchen paper before sowing a whole tray. Our seed-viability checker walks you through the test.