Spring onions, often called salad onions, are quick, uncomplicated crops for beds, containers and allotments. Their mild white shafts and fresh green leaves are useful in summer cooking, while close sowing makes them ideal for filling short rows between slower vegetables.

When and how to sow

Choose an open, sunny site with fertile, moisture-retentive soil. From March to July, sow seed directly in shallow drills, little and often, for continuous summer pulling; repeat sowings in cooler northern gardens. Cover lightly, water gently and thin seedlings just enough to prevent crowding. 'White Lisbon' is a classic. In mild districts, sow hardy 'White Lisbon Winter Hardy' in August or September for spring crops.

Care

Keep the surface evenly moist, particularly during dry spells, because roots are shallow. Weed carefully so stems are not disturbed. A light mulch between rows conserves moisture and reduces competition, but leave the bases clear. Incorporate garden compost before sowing; extra feeding is rarely needed in good ground. Rotate alliums around the plot.

Common problems

Onion fly can make seedlings wilt or collapse, while downy mildew causes pale patches and greyish growth in damp weather. Cover young rows with insect-proof fleece, thin lightly for airflow, and water soil rather than foliage. Remove affected material and rotate onions and crops away from that ground for several seasons.

Harvest

Begin pulling spring onions when stems are roughly pencil-thick and leaves are upright, usually from early summer onwards. Ease compacted soil first with a hand fork, then lift whole plants. Use promptly for flavour, or keep unwashed plants chilled and loosely wrapped for a few days.

Growing Spring Onions: frequently asked questions

When should I sow spring onions in the UK?

Choose an open, sunny site with fertile, moisture-retentive soil.

What are common problems when growing spring onions?

Onion fly can make seedlings wilt or collapse, while downy mildew causes pale patches and greyish growth in damp weather.

When is spring onions ready to harvest?

Begin pulling spring onions when stems are roughly pencil-thick and leaves are upright, usually from early summer onwards.

General guidance for UK home gardens and allotments. Reference figures are typical values; your exact timing depends on your region, last-frost date and variety. Page updated 19 Sep 2026.