When to Harvest Spring Onions
One of the pleasures of spring onions is how little waiting they involve. Sow a short row in spring and you could be pulling them for salads about two months later, long before the maincrop onions have even thought about bulbing up. The trick isn't really knowing when they're ready, it's pulling them steadily so you never end up with a row of coarse, overgrown ones all at once.
Quick facts
Ready: roughly two months from sowing
Main season: late spring through to autumn from spring sowings
Overwintered crops: ready from March
Ideal size: around 15 cm tall, with the base no more than 1–2.5 cm across
How to pick: lift individual plants as you need them
How to tell when spring onions are ready
Spring onions don't give you an obvious signal in the way that, say, onions flopping over do. Instead, you judge them by size:
The green tops stand around 15 cm tall.
The white base has thickened to somewhere between 1 cm and 2.5 cm across, depending on the variety.
The leaves are upright, firm and a healthy green.
There's no single right moment. They can be eaten much smaller as slender salad onions, or left a little longer for a stronger flavour and a fatter base. Young ones taste sweet and mild, and the flavour sharpens the bigger they get.
The harvest season
The timing depends entirely on when you sowed:
Sown March onwards: ready from late spring, with a fresh batch coming through all summer and into autumn.
Sown a short row at a time, a fortnight apart: the surest way to have some at usable size continuously instead of all at once.
Hardy varieties sown in late summer or early autumn: overwinter in the ground and are ready to pull from March.
Sowing dates for each of these are in when to plant spring onions in the UK
How to harvest
Spring onions have shallow roots, but they can still snap if the soil is dry and firm.
Water the row an hour or two beforehand if the ground is dry, which loosens everything and makes lifting easier.
Ease a hand fork in alongside the row to lift the soil slightly.
Hold the plant low down, right at soil level, and pull steadily upwards rather than yanking at the leaves.
Shake off the soil and trim the roots.
Take only what you need for that meal, leaving the rest where they are. Whatever stays in the ground carries on growing.
Harvesting a few at a time
Because you pull individual plants rather than clearing a row, harvesting doubles as thinning. Taking out every other plant gives the ones left behind more room and air, which helps keep downy mildew at bay. Start with the thickest and leave the slimmer ones to size up.
Leaving them too long
Spring onions don't have a hard deadline, but they do deteriorate. Left in the ground too long they grow coarse, the flavour turns harsh, and eventually the base starts to swell into a small bulb. In warm weather or after a check in growth, plants may also run to seed, sending up a flower stem and going tough. If that happens, pull them and sow a fresh batch.
Harvesting from containers
The method is no different for pots and window boxes, and if anything easier, since compost is looser than garden soil. Give the pot a good water beforehand if the compost has dried out. More on growing them this way is in growing spring onions in containers
After harvesting
Spring onions aren't a storing crop. They're at their best within a day or two of lifting, so pull only what you need. In the fridge, wrapped loosely, they'll keep for about a week. Standing them upright in a jar with a little water in the bottom keeps them crisp for a few days longer.
For sowing, spacing and care through the season, see how to grow spring onions in the UK, and for watering, how often to water spring onions
Common questions
How long do spring onions take to grow?
About two months from sowing to a usable size, although they can be pulled smaller if you want slender salad onions.
What size should spring onions be when harvested?
Roughly 15 cm tall with a base of 1–2.5 cm across, depending on the variety. Smaller ones are milder and more tender.
Can you harvest spring onions in winter?
Hardy varieties sown in late summer or early autumn will stand through winter, often under a cloche or fleece, and are ready to pull from March.
Do spring onions keep growing after you pick them?
Whatever you leave behind keeps growing, which is exactly why it pays to pull just a handful at a time. Once pulled, though, a spring onion doesn't regrow from the roots in the garden.
Timings, harvest size and sowing seasons based on RHS guidance.