How to Grow Green Onions Indoors From Scraps (Free, Endless Scallions)

Last updated: 25.06.2026.

This is the gateway drug of indoor growing. You buy green onions, use the green tops for cooking, and instead of throwing away the white root ends, you stick them in a glass of water on the windowsill. Three days later they are visibly taller. A week later you are cutting fresh green onions you already paid for once. It feels a little like cheating.

Green onions (scallions, spring onions, whatever you call them) are the easiest edible thing you can grow indoors, they cost nothing because you are regrowing kitchen scraps, and they need almost no skill. If you have ever wanted to grow food in an apartment but felt intimidated, start here. You genuinely cannot fail.

Why green onions are perfect for this

Green onions store energy in their white base and roots, and when you cut the green tops, the plant simply grows them back from that stored energy. Unlike most vegetables, you do not need seeds, soil, or even much light to get going. The roots are already there on the supermarket bunch. You are just giving them water and a windowsill.

It is the ideal first grow for a tiny space: a Brooklyn studio sill, a London flat kitchen, a Berlin Altbau windowsill. No equipment, no cost, instant results. And it teaches you the basic rhythm of growing food before you invest in anything bigger.

The water method (start here)

The simplest way, and the one that hooks everyone:

1. Buy green onions and use the green tops as normal in cooking.
2. Keep the white root ends, about 2 inches (5 cm) long, with the roots still attached.
3. Stand them root-down in a glass with enough water to cover the roots but not the whole stalk. A narrow glass or jar keeps them upright.
4. Set the glass on a windowsill with some light. They are not fussy, but a brighter spot grows them faster.
5. Change the water every 1 to 2 days. Fresh water keeps them from getting slimy and smelly, which is the only thing that goes wrong with this method.

That is it. You will see new green growth within a couple of days, and you can start snipping the tops within a week or so. Cut what you need and let them keep regrowing.

How long water-regrowing lasts (and why to move to soil)

Here is the honest limit: green onions regrow several times in plain water, but each round gets a little thinner and weaker because the plant is running down its stored energy with nothing to replace it. Water gives them nothing to eat.

After two or three harvests, the green onions in water start to look sad. That is your cue to either start a fresh batch from new scraps, or pot them up in soil, which keeps them going far longer.

The soil method (for endless green onions)

Move them to soil and they become a near-permanent supply, because soil actually feeds them:

1. Take your rooted green onion bases (from the store or after a round in water).
2. Plant them root-down in a pot of organic potting mix, with just the white base buried and the cut tops poking above the soil. A pot 6 inches (15 cm) deep with a drainage hole is plenty.
3. Water so the soil stays lightly moist, never soggy, the same gentle balance that avoids root rot in any plant.
4. Give them a bright windowsill, or a grow light if your spot is dim (the do you need a grow light guide helps you decide).
5. Harvest by snipping the green tops about an inch above the soil, leaving the base to regrow.

In soil, with light and the occasional weak feed, the same green onions regrow again and again for months. Snip what you need for a recipe and they keep coming back.

A few tips that help

• Cut, do not pull. Snip the green tops with scissors and leave the white base and roots in place to regrow. Pulling the whole thing ends it.
• Brighter is faster. They grow in low light but a sunny sill gives you thicker, faster regrowth.
• Change water often in the water method. Stale water is the only failure point. Fresh water every day or two prevents slime and smell.
• Start a rolling supply. Keep a glass or pot going at all times and you will rarely buy green onions again.
• Use them generously. The more you snip (within reason), the more they produce, like most cut-and-come-again greens.

Green onions are the perfect confidence-builder. Free, foolproof, fast, and genuinely useful in the kitchen. Once you have watched kitchen scraps turn into a steady supply of fresh scallions on your windowsill, growing other things stops feeling intimidating. From here, fresh herbs are the natural next step, and basil, mint, and the wider grow herbs indoors without sunlight guide pick up where this leaves off.