Onion Microgreens
Allium cepa
Widely adapted, day-neutral, and matures well anywhere in North America from spring sowing. Suitable for fall planting where short-day onions are normally grown. Produces uniform, large, white-skinned onions with mild flavor and thick rings. Not for long storage. Sierra Blanca is the same variety as Super Star. It has been renamed by the breeder. AAS Winner. Also offered as plants and as conventional seed with NOP-compliant pelleting.
Harvest
109d
Days to harvest
Sun
Full sun
Zones
5–10
USDA hardiness
Height
12-18 inches
Planting Timeline
Showing dates for Onion Microgreens in USDA Zone 7
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Onion Microgreens · Zones 5–10
Growing Details
Zone-by-Zone Planting Calendar
| Zone | Indoor Start | Transplant | Direct Sow | Harvest |
|---|---|---|---|---|
| Zone 3 | January – December | — | — | January – December |
| Zone 4 | January – December | — | — | January – December |
| Zone 5 | January – December | — | — | January – December |
| Zone 6 | January – December | — | — | January – December |
| Zone 7 | January – December | — | — | January – December |
| Zone 8 | January – December | — | — | January – December |
| Zone 9 | January – December | — | — | January – December |
| Zone 10 | January – December | — | — | January – December |
Complete Growing Guide
Light: Full sun (6 or more hours of direct sunlight a day). Soil: High Organic Matter, Loam (Silt), Sand. Soil pH: Alkaline (>8.0), Neutral (6.0-8.0). Drainage: Good Drainage, Moist. Height: 1 ft. 0 in. - 1 ft. 6 in.. Spread: 0 ft. 6 in. - 1 ft. 0 in.. Spacing: Less than 12 inches, 12 inches-3 feet. Maintenance: Medium. Regions: Coastal, Mountains, Piedmont.
Harvesting
Flowers wither and convert to bulblets
Type: Capsule.
Harvest time: Summer
Bloom time: Summer
Storage & Preservation
Fresh onion microgreens are highly perishable and should be used within 3-5 days of harvest for optimal flavor and texture. Store unwashed microgreens in the refrigerator at 35-40°F in a breathable container lined with paper towels to absorb excess moisture. Avoid plastic bags which trap humidity and accelerate decay.
For short-term storage, place cut microgreens in a glass of water like fresh herbs, covering loosely with a plastic bag and refrigerating. Change the water daily to maintain freshness.
Onion microgreens don't preserve well through traditional methods due to their delicate structure and high water content. However, you can freeze-dry them for long-term storage as a seasoning – the hollow stems dehydrate completely while retaining much of their onion flavor. Avoid freezing fresh microgreens as they become mushy when thawed. For continuous supply, succession plant new trays every 5-7 days rather than trying to preserve harvested microgreens.
History & Origin
Onion microgreens represent a relatively recent innovation in the broader microgreen movement that began gaining momentum in the 1980s California culinary scene. While onions themselves have been cultivated for over 5,000 years, originating in Central Asia and spreading throughout ancient civilizations, the concept of harvesting onion plants at the microgreen stage emerged only in the past 30 years.
The microgreen trend was pioneered by chef Todd Koons and others in San Francisco restaurants who sought intense flavors and visual appeal in small packages. Onion microgreens specifically gained popularity in the 1990s as chefs discovered that the hollow, tube-like cotyledons of onion seedlings provided the familiar onion flavor in a more delicate, visually striking form than mature green onions.
Unlike many microgreen varieties that use specific cultivars, onion microgreens can be grown from standard onion varieties including yellow, red, and white storage onions. The practice expanded beyond restaurants into home growing in the 2000s as hydroponic equipment became more accessible. Today, onion microgreens are valued both for their culinary applications and their concentrated nutritional content, containing higher levels of certain antioxidants than mature onions.
Advantages
- +Disease resistance: Black Walnut, Deer, Rabbits
Considerations
- -Toxic: Low severity
Companion Plants
Plant Together
Basil
Repels aphids and thrips that commonly attack microgreens
Chives
Natural fungicide properties help prevent damping-off disease
Parsley
Attracts beneficial insects and doesn't compete for light in microgreen setups
Lettuce
Similar growing conditions and onion microgreens may deter lettuce pests
Cilantro
Complementary growth rates and helps repel spider mites
Arugula
Benefits from onion's pest-deterrent properties, especially flea beetles
Radish Microgreens
Onions help repel root maggots that can affect radish seeds
Spinach
Onion compounds help deter aphids that commonly attack spinach
Keep Apart
Fennel
Allelopathic compounds inhibit germination and growth of most plants
Beans
Onion compounds can inhibit nitrogen fixation and bean germination
Sage
Strong aromatic oils may inhibit delicate microgreen germination
Nutrition Facts
Per 100g serving. % Daily Value based on 2,000 calorie diet. Source: USDA FoodData Central (FDC #170000)
Pests & Disease Resistance
Resistance
Pink Root (Intermediate)
Common Pests
Thrips occasionally, onion maggots (rare in microgreen stage)
Diseases
Damping off, purple blotch in humid conditions, white rot in contaminated soil
Frequently Asked Questions
How long do onion microgreens take to grow?▼
Are onion microgreens good for beginners?▼
Can you grow onion microgreens without soil?▼
What do onion microgreens taste like compared to regular onions?▼
Why are my onion microgreens turning yellow and dying?▼
Do I need to soak onion seeds before planting microgreens?▼
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