Scallion (Allium fistulosum 'Evergreen')

Overview

The Allium fistulosum ‘Evergreen’, commonly known as Scallion or Welsh onion, is an invaluable perennial bulb renowned for its constant supply of strongly flavored, onion-flavored leaves. Distinct from common bulb onions, this variety is prized as a clumping, slowly-spreading type with scarcely developed underground bulbs, making the entire green stature useful. Gardeners appreciate Allium fistulosum ‘Evergreen’ for its near year-round usability in mild climates, providing zesty freshness when other edibles are scarce.

This versatile plant reaches heights between one and three feet and forms clumps that gradually spread, offering consistent harvests. While primarily grown as a vegetable, its structure provides a fine, upright accent in the herb garden, topped by attractive globular umbels of greenish-white flowers in late spring and summer. Its hardiness across USDA Zones 3 through 9 confirms its reliability across diverse gardening environments.

Fast Facts

• Plant Family: Amaryllidaceae
• Plant Type: Bulb
• Hardiness Zones: USDA Zones 3-9
• Size at Maturity:
  • Height: 1-3 ft
  • Spread: 1-2 ft
• Bloom Time: May
• Bloom Description: Greenish white
• Sun Exposure: Full sun
• Water Needs: Medium
• Maintenance Level: Medium

How to Grow

For optimal growth, plant the Scallion in rich, deep, well-drained, sandy-limey loams. While it thrives best in full sun, Allium fistulosum ‘Evergreen’ can tolerate partial shade. Where winter conditions are mild (Zones 6-9), this perennial bunching onion can often be harvested year-round, while in colder regions north of Zone 6, it is best treated as an annual.

When establishing new plants grown as an annual, sow seeds in early spring for summer harvest. Plant them about 1/2” deep, spacing them between 1/4” and 1/2” apart. Consistency is key during the growing season; ensure medium moisture levels are maintained. Perennial divisions are easy, allowing established gardeners to propagate healthy clumps simply.

Garden maintenance involves providing regular but shallow cultivation, which is crucial for suppressing weed competition immediately around the base of the plant. In milder zones, established clumps of this Scallion will spread slowly over time, but they are generally easy to manage.

Landscape Uses

The primary role of Allium fistulosum ‘Evergreen’ in the landscape is functional, centered around its continuous culinary harvest. It excels when integrated into dedicated vegetable gardens or raised beds where its linear, blue-green leaves offer vertical texture. Because its leaves are tasty when young but less ornamental when fully mature, situate it behind shorter edible borders or alongside flowering herbs.

This robust onion serves as an excellent low-maintenance substitute for chives or leeks in the landscape design, adding an edible element near the kitchen door. Its hollow, leafless flowering stalks, topped by attractive umbels in May, provide late-season visual interest before the foliage dies back in harsh winters (though the ‘Evergreen’ cultivar often remains green longer than other types).

Standout Features

Flower Qualities

• Showy
• Fragrant

Noteworthy Characteristics

Allium fistulosum, commonly called spring onion, Welsh onion, or Japanese bunching onion, is a clumping, slowly-spreading, evergreen perennial onion that is primarily grown as a vegetable for harvest of its tasty onion-flavored leaves. It is green like chives, but with larger leaves and a stronger, zesty flavor and can be picked anytime the ground is not frozen. The flowering stalks rise up to 36” tall, topped by globular terminal umbels containing tiny, yellowish-white flowers that bloom from late May to August.

Tolerances

• Deer
• Black Walnut

Potential Problems

Onions, including this Scallion, face susceptibility to several common diseases and pests. Watch for fungal issues like botrytis, purple blotch, and downy mildew, as well as neck rot. Common pests include bothersome onion thrips, the allium leaf miner, and the onion fly, also known as the onion maggot.

Prevention centers largely on soil health and proper drainage. Rotting issues are significantly more likely if the soil remains overly moist or poorly drained, so amending heavy soil is paramount before planting Allium fistulosum ‘Evergreen’. Furthermore, gardeners can rely on the fact that this plant is generally avoided by deer and rabbits.

Frequently Asked Questions

What hardiness zones is Scallion suitable for?

Allium fistulosum ‘Evergreen’ is highly adaptable, thriving in USDA Zones 3 through 9.

How large does Allium fistulosum ‘Evergreen’ grow?

This bunching onion typically reaches a mature height between 1 to 3 feet tall, with a spread of 1 to 2 feet wide.

What sun exposure does Scallion need?

This variety performs best when situated in full sun conditions, although it can tolerate some degree of partial shade.

When does Scallion bloom?

The flowering time is typically in May, producing distinctive, greenish white, globe-shaped flower clusters.

Conclusion

The Allium fistulosum ‘Evergreen’ Scallion provides exceptional value to the home gardener due to its evergreen character and reliable, zesty harvest throughout much of the year. This dependable bulb forms the backbone of many culinary patches, offering flavor far beyond its simple maintenance needs. Before planting, confirm your USDA hardiness zone compatibility and plan for rich, well-draining soil to maximize the productivity of your Allium fistulosum ‘Evergreen’.

Companion Planting

This perennial bunching onion makes an excellent companion for brassicas and carrots, as its strong sulfurous scent can help deter common root fly pests that target those vegetables. Avoid planting near beans or peas, as onions can sometimes inhibit the growth of legumes. Establishing clumps of Scallion around tomatoes can also contribute to the overall health of the vegetable garden ecosystem.

Seasonal Care Calendar

For growers treating the Scallion as an annual in cold regions, initiate sowing seeds indoors or directly outdoors in early spring once the soil is workable. Throughout the primary growing season (late spring through early fall), focus on consistent watering to meet its medium moisture needs and ensure regular shallow cultivation to control weeds. In climates where this variety survives winter, minimal protection is usually needed; however, ensuring good drainage before the onset of wet, cold weather will prevent winter rot in established perennial clumps.