very easy · windowsill
How to grow spring onions
Almost impossible to fail with, and they regrow after cutting — one sowing can crop several times.
Allium fistulosum · Amaryllidaceae
Why bother
They take up almost no room, tolerate a lot of neglect, and the regrowth trick makes the point about home growing better than almost anything else.
What it needs
- Light
- 4+ hours of sun. Tolerates a less-than-perfect windowsill.
- Water
- Keep evenly moist. They are shallow-rooted and dry out fast in small pots.
- Soil
- Any general-purpose compost.
- Temperature
- Wide tolerance, roughly 10-30C.
- Container
- A 20cm pot holds a useful clump. Depth matters less than width.
- Time to harvest
- 8 weeks from seed, or about 3 weeks if regrowing from roots.
Step by step
Day 0
Sow or regrow
From seed: sow 1cm deep, 2cm apart. From shop-bought: keep the bottom 3cm with roots attached and plant it root-down in compost.
Week 1-2
Water and wait
Keep the compost moist. Regrown roots will push new green shoots within a few days; seed takes one to two weeks.
Week 3
Thin if needed
Give each plant about 2cm of space so the stems can thicken.
Week 8 onward
Cut and come again
Snip the green tops about 3cm above the compost and leave the roots in place. They regrow two or three more times before needing replacing.
What usually goes wrong
Thin, floppy stems
Cause: Sown too densely, or too little light.
Fix: Thin to about 2cm apart and move somewhere brighter.
Tips going brown and papery
Cause: Compost drying out between waterings.
Fix: Water more often and less heavily. Small pots dry out surprisingly quickly.
Grows well beside
Carrot, Lettuce
Before you eat anything you grow: be certain of the identification. This guide describes spring onions specifically — it is not a way to confirm that an unknown plant is safe. Never eat a plant on the strength of an app alone.