How to Grow Green Onions (Scallions): A Beginner's Guide

If you're new to growing food, green onions are the perfect place to start. Known as scallions in the US, spring onions in the UK and Australia, and salad onions elsewhere, these slender, mild alliums are fast, forgiving, and almost impossible to fail with. You can grow them from seed, from sets, or even regrow them from kitchen scraps on a windowsill. In as little as eight weeks you'll be snipping fresh, crisp greens into salads, stir-fries, tacos, and soups.

Here's everything you need to know to grow green onions, wherever you garden.

What exactly is a green onion?

Green onions, scallions, and spring onions are essentially the same thing: young onions harvested before they form a large bulb. You eat the whole plant — the white base and the green tops. The flavour is milder and fresher than a mature onion, which is why they shine raw as a garnish.

Some are grown from true onion varieties pulled young; others come from bunching onion types (*Allium fistulosum*) that never bulb at all and are perfect for repeat harvests.

When to sow

Green onions are quick and cold-tolerant, so you have a generous window:

Northern Hemisphere: Sow from early spring through late summer (March–August) for harvests spring through autumn. Hardy bunching types sown in late summer can overwinter for an early spring crop.

Southern Hemisphere: Sow from early spring through summer (September–February).

Because they mature so fast, green onions are an ideal candidate for succession sowing — plant a short row every two to three weeks and you'll never be without them. Always check your local last-frost date for the earliest outdoor sowings, though these plants handle light frost well.

How to sow

Green onions don't need much space, which makes them brilliant for containers, window boxes, and the edges of raised beds.

1. Sow seeds thinly, about 1 cm (½ in) deep, in rows 15 cm (6 in) apart — or scatter them in a pot at least 15 cm (6 in) deep. 2. Keep the soil at around 18–21°C (65–70°F) for fastest germination, which takes one to two weeks. 3. Thin seedlings to about 2.5 cm (1 in) apart. Don't throw the thinnings away — they're edible!

Unlike bulb onions, you don't need wide spacing because you're harvesting them young.

Growing in containers and on windowsills

Green onions are one of the best crops for small-space and indoor growing. A pot on a sunny balcony or a bright windowsill (receiving at least 6 hours of light) will produce a steady supply. Use a free-draining potting mix and keep it lightly moist.

The kitchen-scrap trick: Next time you buy green onions, save the white root ends with about 2.5 cm (1 in) of stem. Pop them root-down in a glass of water or a pot of soil on the windowsill, and they'll regrow new green tops within a week or two. It's a fun, free way to keep the supply going — and a great project to share with kids.

Caring for green onions

These are about as low-maintenance as vegetables get:

Water consistently. Even moisture keeps the greens tender and prevents them turning tough or pungent.

Weed gently, as their shallow roots dislike disturbance.

Feeding is rarely needed in decent soil, but a weak liquid feed every few weeks helps container plants.

Pests and problems

Green onions are largely trouble-free. In regions where allium leaf miner or onion fly are present, a layer of insect-proof mesh keeps them out. Good airflow and avoiding waterlogged soil prevents most fungal issues. As with all alliums, rotate where you grow them year to year.

Harvesting

This is the easy part. Harvest green onions once they're about 15 cm (6 in) tall and pencil-thick — usually 8 to 10 weeks from sowing.

You have two choices:

Pull the whole plant for that classic white base and green top.

Cut-and-come-again: Snip the green tops 2.5 cm (1 in) above the soil and leave the roots in place. Bunching types will regrow several times, giving you multiple harvests from one sowing.

Harvest in the morning when the greens are crispest, and use them fresh — they don't store long, which is all the more reason to grow your own.

Share the bounty

Because green onions grow so fast and crop again and again, a single packet of seeds can produce far more than one household needs. They're the perfect crop to share fresh with neighbours, or to swap for someone else's tomatoes or herbs. Small, generous exchanges like these are what turn a street of gardeners into a community.

Want to swap and share your homegrown produce with people nearby? Join Locavori today and start connecting with growers in your neighbourhood.