vegetable
allium family

Spring Onion

Allium fistulosum

Spring onions are one of the quickest and easiest salad crops, ready to harvest just 8–12 weeks after sowing. They take up very little space and can be tucked in between slower-growing crops, making them perfect for intensive allotment gardening. Sow seed thinly in drills 1cm deep from March to September for a near-continuous harvest from late spring to autumn. Successional sowing every 3–4 weeks ensures you never run out. Hardy varieties like 'White Lisbon Winter Hardy' can be sown in September and October to overwinter, providing the earliest spring harvest. They grow happily in containers, window boxes, and grow bags. No thinning is needed — simply pull individual onions as required, or harvest whole clusters. They prefer fertile, moisture-retentive soil in full sun or light shade. Water in dry weather to prevent the bulbs becoming tough and overly pungent. Japanese bunching onions (A. fistulosum) are a perennial alternative that can be harvested repeatedly. 'Performer' is excellent for summer crops; 'Guardsman' for its upright, uniform growth; and 'North Holland Blood Red' for striking red-skinned bulbs.

Plan where to grow Spring Onion using our vegetable garden planner.

SunlightFull sun
WateringModerate
Height30cm
Spacing2cm
Germination12–18 days
Sowing MethodDirect sow
Frost HardinessHardy
Sowing Depth1cm

When to Sow Spring Onion

Sow spring onion in March, April, May, June, July, August, September, October.

Jan
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Sowing months

Time to Harvest Spring Onion

Expect to harvest approximately 2 months after sowing.

Companion Plants

Expected Yield

Very quick crop; a 1m row produces 30–40 spring onions in 8–12 weeks.

Growing Tips

Sow successionally every 3–4 weeks for continuous harvest

Common Problems with Spring Onion

Onion fly

Small white maggots bore into the base of the bulb, causing yellowing and wilting leaves. The flies are attracted by the scent of bruised foliage, so avoid thinning (which isn't needed for spring onions anyway). Cover with enviromesh from sowing to harvest to prevent egg-laying. Grow alongside carrots — the onion scent deters carrot fly in return.

Bolting (running to seed)

Spring onions sown too early in cold conditions, or those subjected to sudden temperature fluctuations, may bolt — sending up a flower stalk instead of forming a usable bulb. Sow at the right time for your area, and use bolt-resistant varieties like 'Performer' for early sowings. Bolted plants are still edible but tougher.

Downy mildew

Leaves develop grey-purple fuzzy patches and turn yellow from the tips down, especially in wet, humid weather. Avoid overhead watering, ensure good spacing for air circulation, and remove affected foliage. Rotate allium crops annually. Worst in cool, damp autumns on overwintering crops.

Plan your spring onion in the allotment planner

Drag and drop plants onto your plot and get personalised sowing reminders.

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