How to Grow Bombay Onion
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Bombay Onion
Allium cepa var. cepa
vegetableBombay onions are a large, pungent red onion variety known for their deep burgundy-red skin and layers. They are storage onions with a sharp, spicy flavor that mellows when cooked, making them versatile for both raw and cooked applications. This heirloom variety is prized for its exceptional keeping quality and distinctive appearance.
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Example Bombay Onion timeline · Pittsburgh, PA (Zone 6b)
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Plant Bombay 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 Bombay Onion
Around Aug 15≈ 120 days after planting
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Growing Conditions
Soil
Growing Zones
Find your zone →Thrives in zones 3-9; can be grown in zones 2-10 with adjusted timing
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Sprouting
1-2 weeksSmall green shoots emerge from the onion set within 7-10 days. Root system develops below soil.
Keep soil consistently moist but not waterlogged. Ensure adequate drainage. Thin seedlings to proper spacing if starting from seed.
Vegetative Growth
8-10 weeksGreen foliage develops with multiple upright leaves. Plant builds root system and establishes vigor. Leaves can reach 12-18 inches tall.
Maintain consistent watering (1-2 inches per week). Apply balanced fertilizer every 3-4 weeks. Mulch around base to retain moisture and suppress weeds. Remove any flower scapes that appear.
Bulbing
4-6 weeksBase of plant swells as bulb enlarges. Foliage remains green and upright. Bulb develops characteristic layers and deep red coloration.
Reduce nitrogen fertilizer; increase phosphorus and potassium. Continue regular watering but allow soil to dry slightly between waterings. Do not hill soil over bulbs—they develop best with shoulders exposed to light.
Maturation & Curing
2-3 weeksTops yellow and begin to fall over naturally. Bulb skin dries and papery layers form. Plant gradually reduces water uptake.
Stop watering once tops fall over. Allow bulbs to cure in the ground for 1-2 weeks in dry weather if possible. Do not break off tops prematurely. Handle gently to avoid bruising.
Harvest & Storage
Storage phaseTops are completely dry and brown. Bulbs are firm with dry, papery skin ready for harvest.
Pull bulbs or loosen soil and lift carefully. Cure in warm, dry location (70-75°F) with good air circulation for 2-3 weeks before trimming tops. Store in cool (32-40°F), dry location with 60-70% humidity for extended shelf life (6+ months).
Common Pests
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Use floating row covers over young plants; practice crop rotation; remove debris promptly; apply spinosad or neem oil if infestation occurs
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Spray with neem oil or insecticidal soap; remove infested leaves; encourage beneficial insects; avoid over-fertilizing with nitrogen
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Protect with row covers; use yellow sticky traps; apply diatomaceous earth around base; practice sanitation and crop rotation
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Increase humidity with water spray; use miticides if needed; encourage predatory mites; ensure adequate moisture
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Create barriers around seedlings; remove debris and weeds; use Bacillus thuringiensis (Bt); hand-pick if found
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Practice strict crop rotation (3+ years); use disease-free sets; ensure excellent drainage; remove infected plants immediately; sterilize tools
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Improve air circulation; avoid overhead watering; apply sulfur dust or fungicidal spray; remove affected foliage
Uses
Raw & Caramelized Cooking
CulinaryBombay onions add pungent bite to fresh salads, salsas, and garnishes. When cooked slowly, their sharp flavor transforms into sweet, complex notes ideal for French onion soup, caramelized dishes, and stews. [source]
Pickling & Preservation
CulinaryTheir firm flesh and storage capability make them excellent for pickling, fermentation, and extended pantry storage. Red onion color creates visually striking pickled preparations. [source]
Anti-inflammatory & Antioxidant Properties
MedicinalOnions contain quercetin and other polyphenols with anti-inflammatory and antioxidant effects. Traditionally used to support immune function and respiratory health. [source]
Natural Dye & Cleaning
HouseholdRed onion skins produce natural dyes for fabrics and can be used in traditional dyeing processes. Onion juice has mild antimicrobial properties for household cleaning applications. [source]
Pollinator Garden Support
WildlifeIf allowed to bolt and flower, onion flowers attract bees and beneficial insects, supporting pollinator populations and garden biodiversity. [source]
This is not medical advice. LizPlants is not a medical resource. Always consult a qualified healthcare professional before using plants medicinally.
Harvest Tips
Harvest when tops fall over naturally and soil dries out (typically late July-August in northern regions). Gently loosen soil with a fork and lift bulbs carefully. Cure in a warm, dry, well-ventilated location (not in direct sun) for 2-3 weeks to allow skin to harden and outer layers to papery texture. Trim roots to 0.5 inches and cut dried tops to 1-2 inches. Store in mesh bags or braided strings in a cool (32-40°F), dry location with moderate humidity for best long-term storage (6+ months). Handle carefully to avoid bruising, which promotes rot.
Fun Facts
- 🌱 Bombay Red onions are named after Mumbai (formerly Bombay), India, where this heirloom variety has been cultivated for centuries and remains highly valued for storage and flavor.
- 🌱 A properly cured Bombay onion can last 6-8 months in cool storage, making it one of the longest-keeping onion varieties—ideal for self-sufficient gardeners and historical food preservation.
- 🌱 The red pigment in Bombay onions (anthocyanins) not only gives them their distinctive color but also provides significant antioxidant benefits, with deeper red varieties containing higher concentrations than yellow or white onions.
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