Salad Onions

Salad onions, also called spring onions or scallions, are quick, compact crops that fit into small vegetable plots and containers. Their mild young stems and leaves can be eaten raw in salads or cooked in stir-fries. They are usually raised from seed and take about two months to reach harvest size.

Sow small batches every couple of weeks for a continuous supply, or choose a cultivar with a naturally long harvest period and make a larger sowing. Hardy varieties can be sown in late summer or early autumn, overwintered as small plants and lifted from March onward. These autumn crops benefit from cloches or biodegradable fleece in harsh weather.

Salad onions may belong to Allium cepa or Allium fistulosum. Some form narrow white shafts like miniature leeks, some develop small rounded white bulbs, and others have reddish-purple skin. Harvesting young keeps the flavour sweet and mild; larger plants become stronger.

Match the cultivar to your preferred appearance and season. Long white non-bulbing stems are useful when a uniform shaft is wanted, while small purple bulbs add colour to salads. Choose hardy cultivars for overwintering and RHS Award of Garden Merit selections for proven garden performance.

Recommended varieties

Salad onion ‘Photon’

Produces straight, elongated white stems and good yields across a long June-to-October harvest period.

Cultivar sourceAllotment Pro variety guide

Salad onion ‘White Lisbon’ AGM

A long-established, quick-growing favourite suited to repeat sowing and overwintering.

Cultivar sourceAllotment Pro variety guide

Salad onion ‘Guardsman’ AGM

A vigorous cultivar with tall upright leaves that is slow to swell into bulbs.

Cultivar sourceAllotment Pro variety guide

Salad onion ‘Apache’ AGM

A fast-growing mild cultivar with purple-skinned small bulbs and dark-green leaves.

Cultivar sourceAllotment Pro variety guide

Salad onion ‘Ishikura’ AGM

Forms long straight white stalks without swollen bulbs and can be harvested at many stages over an exceptionally long period.

Cultivar sourceAllotment Pro variety guide

Choose a sunny site with free-draining soil and remove perennial and annual weeds thoroughly. Salad onions have a limited root system, so add about one bucketful of homemade garden compost or well-rotted manure per square metre. This supplies nutrients, improves structure and helps the soil hold moisture. Do not use fresh manure. Rake the surface to a fine, level tilth without large stones or lumps.

In a no-dig bed, apply a mature organic mulch before sowing and create a fine surface for the shallow drills. Avoid low ground that remains saturated in winter, especially for autumn-sown crops.

For container growing, use a pot at least 30cm wide, fill it with peat-free multipurpose compost, water before sowing and place it in a warm sunny position. A greenhouse container extends the sowing season, but it still needs ventilation and regular moisture checks.

Direct outdoor sowing is simplest. From March, make a shallow drill 1cm deep, water along its base, sow seed thinly and cover with soil. Leave about 20cm between rows. Repeat a small sowing every two weeks for overlapping harvests. Hardy cultivars can also be sown in late summer and early autumn; they should establish as compact plants before winter and become ready from March.

Thin seedlings to about 2.5cm apart, using suitable thinnings in salads. Closer permanent spacing restricts airflow and can encourage downy mildew. Protect young plants from slugs and snails, particularly in damp weather.

If soil is cold or wet in early spring, sow in modular trays indoors in March. Alternatively sow in a greenhouse border or final large container. Once module-grown plants are well rooted and growing strongly, harden them off and transplant later in spring a few centimetres apart. Water before and after planting.

In a 30cm or wider container, scatter seed thinly over watered compost and cover with about 1cm of compost. Thin as the plants establish.

Water seedlings and transplants until established. Thereafter, ground-grown salad onions need additional water mainly during prolonged dry spells. Container compost dries more rapidly and should be checked frequently, especially in hot weather. Water the compost rather than leaving foliage damp overnight.

Keep the crop free from weeds, which compete strongly with the onions’ small root systems. Hoe carefully between rows and hand weed close to individual plants so their roots and stems are not disturbed. Avoid overcrowding and remove damaged foliage to maintain airflow.

Hardy autumn sowings often benefit from cloches or biodegradable fleece through winter. Secure covers against wind and ventilate them during mild spells. Remove protection progressively when active spring growth resumes.

For spring-to-autumn harvests, start outdoor sowing in March and add a short row every two weeks. This avoids a glut and supplies young mild onions rather than a single batch that becomes oversized and strong. Long-season cultivars such as ‘Photon’ or ‘Ishikura’ can broaden the picking window.

For an early spring crop, sow a hardy cultivar outdoors in late summer or early autumn. The goal is to establish small sturdy plants, not large soft growth, before cold weather. Protect in severe conditions and begin lifting from March. Where winter soil is wet or the site is exposed, use a greenhouse container or well-drained protected bed.

Most salad onions reach useful size in about two months. Lift individual plants whenever needed rather than clearing a whole row. The best eating stage is around 15cm tall, with any bulb no more than about 1–2.5cm across, depending on the cultivar. At this size the white base and green leaves are tender and the flavour is mild.

Loosen dry or firm soil first so the stem does not break. Harvest just before use for maximum freshness, wash soil from the base and trim roots and damaged leaf tips. Continue repeat sowing to maintain harvest from spring through autumn. Overwintered rows provide the earliest spring supply.