Zero-Soil Method
How to Regrow Green Onions in a Glass of Water
Keep the white base and roots of a green onion in a glass of water, tips above the waterline, and change the water every few days. New growth usually appears within a week, and you can expect about 2 to 4 good regrows before growth slows and the roots start to turn slimy — at that point, moving the plant to soil gets you more life out of it.
Regrowing in Water at a Glance
| Quick Fact | What to Know |
|---|---|
| What you need | The white base and roots, with at least half an inch of root intact |
| Water change | Every 2 to 3 days to keep it fresh |
| Light | A bright windowsill, indirect is fine |
| Time to new growth | Visible regrowth within about a week |
| Number of regrows | About 2 to 4 before growth thins and roots turn slimy |
| What’s next | Move to soil for longer-lasting, sturdier growth |
How to Do It, Step by Step
- Save the white base of a green onion after cooking, keeping about half an inch to an inch of root attached.
- Stand it in a glass or jar with just enough water to cover the roots and the very bottom of the white base. The green tips should stay above the waterline.
- Put it somewhere bright, like a kitchen windowsill. Direct sun isn’t necessary.
- Change the water every 2 to 3 days. This is the single biggest factor in how long the regrowth stays healthy and odor-free.
- Harvest the green tops as you need them, snipping from the top so the base keeps producing.
- Watch for slowing growth or slimy roots after a few regrowth cycles — that’s your cue to either start a fresh base or move this one into soil.
Why Do the Roots Go Slimy, and What’s Normal?
Some sliming is expected as roots age in standing water; the general range reported by home growers is about 2 to 4 regrowth cycles before it becomes noticeable, though some get a bit further before quality drops off. A faint earthy smell from the roots is normal. A strong, unpleasant odor or cloudy water, though, usually means the water has gone stagnant between changes — the fix is simply changing it more often, and giving the glass itself an occasional rinse to clear any film.
Water vs. Soil: Which Lasts Longer?
| Method | Regrowth Cycles | Effort | Best For |
|---|---|---|---|
| Water (glass) | About 2 to 4 | Lowest — just change the water | Watching it happen, quick kitchen supply |
| Soil | More, and sturdier growth | Slightly higher — needs a pot and soil | Longer-term, more reliable regrowth |
Water is the easiest way to see roots develop and makes a great kitchen-windowsill project, especially with kids. For onions that keep producing well past the first few cuttings, moving the base to soil is the better long-term choice — see our guide to growing green onions from scraps in soil.
Frequently Asked Questions
How often should you change the water?
Every 2 to 3 days. This is the main thing that determines how fresh and odor-free the regrowth stays.
How many times can you regrow green onions in water?
Typically about 2 to 4 times before growth thins out and roots start to go slimy. Moving the base to soil at that point extends its life.
Do green onions regrown in water need sunlight?
A bright spot is enough; direct sunlight isn’t required for the green tops to regrow.
Why do my water-grown green onions smell bad?
Usually stagnant water between changes. Change the water more often and rinse the glass itself occasionally.
Final Thoughts
Regrowing green onions in water is the easiest, lowest-effort way to stretch a single bunch further — just save the base, change the water regularly, and expect a handful of good harvests before it’s time to start fresh or move to soil. For a longer-lasting version of the same trick, see growing green onions from scraps in soil, or head to the main growing guide for bulb onions.
How This Guide Was Checked
Related Onion-Growing Guides
- How to Grow Green Onions (Scallions and Spring Onions)
- Scallion vs Green Onion vs Spring Onion: What’s the Difference?
- Can You Grow an Onion From an Onion? The Honest Answer
See the full How to Grow Onions guide for the complete seed-to-harvest walkthrough.
