Scallion (spring onion)

Sun

Full sun; tolerates light shade, with slower growth.

Water

Keep evenly moist during active growth, especially in containers; avoid saturated soil.

Soil

Fertile, well-drained soil, ideally near neutral pH; raised beds help on heavy clay.

Height

1-2 ft (0.3-0.6 m), with flower stems sometimes reaching 3 ft (0.9 m)

Spread

0.5-1 ft (0.15-0.3 m) per established clump

Flowers

Late spring to summer; rounded heads of small creamy-white flowers.

Foliage

Upright, hollow, tubular green to blue-green leaves; leaf bases form slender white stems without a large rounded bulb.

Growth

Fast in mild weather with adequate moisture.

Care needed

Low

• Pollinators
• Deer resistant
• Low allergen
• Edible

Northern hemisphere months. In Australia, shift them by six.

Difficulty

Easy

Toughness

Fairly tough

Pick your zone, country, light and whether you have pets.

1. Planting day

   1 ft (0.3 m)

2. After 1 year

   1.2 ft (0.38 m)

3. After 2 years

   1.5 ft (0.45 m)

   full size

About 2 years to full size.

From a typical nursery size, at an average rate for this kind of plant. A rule of thumb, not a forecast.

Cats and dogs

Toxic

Native to

Canada

Growth rate

Fast

• Water when the soil surface begins to dry; do not let young plants dry out.
• Mix mature compost into the bed before planting; feed container plants lightly during active growth.
• Keep seedlings free of weeds, hoeing shallowly to avoid their roots.
• Apply a thin mulch around established clumps, keeping it away from the leaf bases.
• Divide crowded clumps every two or three years in spring.

Pruning. Remove yellow or damaged leaves at the base as needed. Cut off flower stems as they develop if you want leafy growth rather than flowers or seed.

Pick outer leaves once plants are well established, cutting above the base and leaving the centre to regrow. For whole scallions, lift plants when the white stems are roughly pencil-thick, often 8-12 weeks after sowing in favourable conditions; leave some plants to form perennial clumps.

Late winter

Sow indoors in bright light if you want an early crop in a cold climate.

Spring

Direct-sow when soil is workable, or transplant hardened-off seedlings; divide established clumps.

Late spring

Begin picking established plants and remove emerging flower stems unless you want flowers or seed.

Summer

Water through dry spells and make small repeat sowings where summers are not excessively hot.

Autumn

Sow for cool-season harvests in mild climates; remove dead foliage from established clumps.

Winter

Harvest lightly where plants remain green; leave dormant outdoor clumps undisturbed and avoid waterlogging.

• Plant in repeated rows along vegetable-bed edges for an upright, orderly outline.
• Grow in kitchen-door containers with parsley and lettuce for convenient picking.
• Use small clumps among leafy vegetables to contrast narrow blue-green leaves with broad foliage.
• Allow a few clumps to flower in an edible border for pale rounded flower heads and visiting insects.

Garden styles it suits: Potager (kitchen garden), Edible landscape, Herb parterre, Cottage garden, Small-space and Homestead.

Plant it with: Lettuce, Carrots, Beetroot, Parsley, Swiss chard and Calendula.

Wildlife: Open flowers provide nectar and pollen for bees and other insects. Plants harvested before flowering offer little floral food.

• Onion fly maggots: use fine insect mesh over young crops where this pest occurs, rotate planting sites and remove infested plants.
• Thrips: look for silvery streaks and distorted leaves; keep plants adequately watered and remove badly affected foliage.
• Allium rust: remove heavily spotted leaves, thin crowded clumps and avoid wetting foliage when watering.
• White rot: yellowing plants with white fungal growth at the base should be lifted and discarded; avoid planting any alliums in affected soil, where the fungus can persist for many years.

All parts are toxic to cats, dogs and horses and can cause serious red blood cell damage if eaten, including when cooked or dried. It is not known to be toxic to people in normal culinary amounts, although onion allergy or digestive intolerance can occur.

• Bulb onion (Allium cepa)

  Young plants can be almost indistinguishable and are also sold as spring onions. Most bulb-onion varieties develop a rounded bulb as they mature; Allium fistulosum remains slender-based and forms clumps.

• Chives (Allium schoenoprasum)

  Chives have much finer hollow leaves and usually pink-purple flower heads, rather than the thicker leaves and creamy-white flowers of scallions.

• Garlic chives (Allium tuberosum)

  Garlic chives have flat, solid leaves and starry white flowers in looser heads; scallion leaves are hollow and tubular.

The species name fistulosum means hollow or tubular, referring to the leaves, while 'Welsh' in Welsh onion comes from an old word meaning foreign rather than indicating an origin in Wales.

Propagation. Sow seed shallowly in spring, or in autumn in mild climates. Divide established clumps in spring, replanting rooted shoots at their previous depth; plants left to flower may also self-seed.

Accepted botanical name

Allium fistulosum

In the US and Canada

Native in Canada. Introduced in Alaska and the lower 48 states.

Native range

China North-Central and China South-Central.

Measured

Soil pH 7 to 7.5. Average height 55 cm.

Sources: GBIF (CC BY 4.0), USDA PLANTS and Trefle (CC BY 4.0). The care and design notes are LandscapeGPT's own.