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Allium cepa 'Superstar'
Superstar Onion
F1 hybrid cultivar; the species A. cepa is native to Central AsiaOverview
Allium cepa 'Superstar' is Superstar onion, a biennial grown as an annual for bulb production, 24-36 inches (60-90 cm) tall and 6-8 inches (15-20 cm) wide — taller and more robust foliage than most onion cultivars. Large globe-shaped bulbs 4-6 inches (10-15 cm) diameter with golden-bronze papery skins and mild sweet white flesh. The largest-bulbing white onion cultivar commonly available: routinely reaches 1-2 pounds (0.45-0.9 kg). Blue-green waxy hollow tubular foliage. In the amaryllis family (Amaryllidaceae). A long-day onion: requires 14-16 hours of daylight for bulbing (latitudes above 36°N). F1 hybrid — seed does not produce true to type. Mild sweet flavor — suited to raw eating and cooking. Stores 3-6 months at 32-40°F (0-4°C) — intermediate storage life (longer than sweet types at 1-2 months, shorter than pungent storage types at 8-10 months). Start seed indoors 10-12 weeks before last frost. Harvest when 50-75% of tops have fallen and yellowed (110-130 days from transplant). The large bulb size requires consistent moisture and fertility — undersized bulbs result from drought or nutrient stress. All Allium contain thiosulfates: toxic to dogs, cats, and horses. Deer-resistant. Full sun. Annual. Growth rate is moderate.
Native Range
F1 hybrid cultivar. The species A. cepa is native to Central Asia (Iran, Afghanistan, Pakistan).Suggested Uses
Grown in vegetable gardens and containers of at least 5 gallons (19 L). The largest white onion. Mild sweet — raw and cooking. Long-day type. Stores 3-6 months. F1 hybrid. Toxic to pets. Deer-resistant. Annual.How to Identify
Appearance
Size & Dimensions
Height2' - 3'
Width/Spread6" - 8"
Reaches mature size in approximately 1 years
Bloom Information
Biennial: flowers in the second year if overwintered — white spherical umbels. Grown as an annual for bulb production. Cut flower scapes at the base if they appear.Detailed Descriptions
Flower Description
White spherical umbels — only if allowed to bolt; undesirableFoliage Description
Blue-green with waxy coating, hollow tubular; taller and more robust than most onion cultivars; yellows at maturityGrowing Conditions
Sun Requirements
Requires 6-12 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Care & Maintenance
Care Guide
Full sun (6+ hours). Rich well-drained soil pH 6.0-7.0. Long-day onion — 14-16 hours daylight. Start seed 10-12 weeks indoors. Consistent moisture and fertility required for large bulbs. Reduce watering as tops yellow. Stores 3-6 months. F1 hybrid. All Allium toxic to pets. Deer-resistant. Annual.Pruning
Cut flower scapes at the base if they appear. Do not cut green foliage during growth. Harvest when 50-75% of tops have fallen. Trim tops to 1 inch (2.5 cm), roots to 0.25 inch (6 mm). Cure 2-3 weeks.Maintenance Level
lowContainer Growing
✓ Suitable for container growing
Minimum container size: 5 gallons