How to Grow Welsh Onion
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Welsh Onion
Allium fistulosum
vegetableWelsh onions are perennial or biennial alliums that form clusters of thin, hollow green stalks rather than large bulbs. Also called bunching onions or scallions, they produce a mild onion flavor and are harvested for both their white bases and tender green tops. This hardy, cold-tolerant crop can be grown year-round in many climates and regrows after harvesting.
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Example Welsh Onion timeline · Pittsburgh, PA (Zone 6b)
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Plant Welsh Onion
Around Apr 17Near Pittsburgh's average last spring frost.
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Tend & protect
Late spring–summerWatering, feeding, and pest-watch reminders.
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Harvest Welsh Onion
Around Jun 1≈ 45 days after planting
Sample dates for Pittsburgh, PA. Sign up to get exact Welsh Onion dates for your own zip code.
Growing Conditions
Soil
Growing Zones
Find your zone →Thrives in zones 3-9; hardy perennial in most temperate regions
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Germination & Seedling
10-14 daysTiny grass-like shoots emerge from soil, developing first true leaves. Seedlings are delicate and light-colored.
Keep soil consistently moist but not soggy. Provide bright light to prevent leggy growth. Thin seedlings to proper spacing once established.
Vegetative Growth
25-40 daysMultiple hollow green shoots develop from the base, forming dense clusters. Plants establish shallow but spreading root systems.
Maintain even moisture and consistent nitrogen supply. Side-dress with compost or balanced fertilizer every 3-4 weeks. Remove any flower stalks if extended harvest is desired.
Bunching & Maturity
Ongoing once maturePlant reaches harvestable size with 6-12 hollow green stems per cluster, each ¼-½ inch diameter. White bases become more pronounced.
Ready for light harvesting; cut outer stems first to encourage continued growth. Can harvest repeatedly without uprooting the plant.
Flowering (if allowed)
Variable, typically mid to late summerTall flower stalks emerge with pale purple or white umbel flowers atop hollow stems. Plant energy shifts to seed production.
Remove flower stalks promptly to maintain tender green production and prevent self-seeding. Allow to flower only if seed saving is desired.
Winter Dormancy/Regrowth
3-4 months in cold regionsIn cold climates, foliage dies back or goes dormant. Plant survives as dormant bulbs/clumps underground and regrows in spring.
Mulch with 2-3 inches of straw or compost in zones below 6. In mild climates, continues slow growth. Divide clumps every 2-3 years.
Companion Planting
Plan your garden →Plant with:
Avoid planting near:
Common Pests
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Use row covers before adults emerge. Apply diatomaceous earth around base. Rotate planting locations yearly. Remove damaged plants promptly.
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Spray neem oil or insecticidal soap every 7-10 days. Encourage beneficial insects. Remove heavily infested leaves.
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No cure; remove and destroy affected plants immediately. Ensure excellent drainage. Don't replant onions in same spot for 5+ years.
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Spray with strong water jet to dislodge. Use insecticidal soap or neem oil. Introduce ladybugs or lacewings.
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Improve air circulation and avoid wetting foliage. Apply sulfur or copper fungicide preventatively in humid conditions.
Uses
Fresh Garnish & Cooking
CulinaryWelsh onions are used fresh in salads, soups, stir-fries, and as a garnish for their mild, sweet onion flavor and decorative green color. Both the white base and tender green tops are edible. [source]
Asian Cuisine
CulinaryA staple in Chinese, Japanese, Korean, and Vietnamese cooking where they're called scallions or green onions. Commonly featured in noodle dishes, dumplings, and as a condiment. [source]
Traditional Medicine & Health
MedicinalUsed in traditional Chinese and Ayurvedic medicine to support digestion, circulation, and immune function. Contains quercetin and vitamin C with potential anti-inflammatory properties. [source]
Companion Planting & Garden Health
HouseholdAlliums naturally repel many pests including aphids, spider mites, and some beetles when planted throughout the garden. Their sulfur compounds deter insects without pesticides. [source]
Beneficial Insect Attraction
WildlifeIf allowed to flower, Welsh onion's umbel flowers attract pollinators and beneficial insects like bees and parasitic wasps that control garden pests. [source]
This is not medical advice. LizPlants is not a medical resource. Always consult a qualified healthcare professional before using plants medicinally.
Harvest Tips
Begin harvesting 45-60 days after planting when stems are 6-8 inches tall and pencil-thin. Cut outer stems 1-2 inches above soil level with a sharp knife to encourage regrowth from the center. Harvest regularly to promote tender new shoots. For continuous supply, succession plant every 2-3 weeks. Can harvest through the growing season; perennial types regrow for multiple years.
Fun Facts
- 🌱 Despite the name 'Welsh' onion, the plant likely originated in Siberia and was brought to Europe via Mongol trade routes, becoming popular in Wales and northern Europe due to its cold hardiness.
- 🌱 Welsh onions are perennial and can be harvested for 3-5 years from the same planting before requiring division or replanting, making them an economical crop.
- 🌱 They're sometimes called 'evergreen onions' because in mild climates they produce fresh growth year-round, providing a continuous harvest of tender greens even in winter when other vegetables are scarce.
Gardening Terms
New to gardening? Learn about terms used in this guide:
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