VegetableOnion
Superex Yellow Onion
Superex Yellow Onion is a short-day hybrid that thrives in tropical and subtropical climates, delivering 160 days to a flattened globe bulb with mild, sweet flavor. Its yellow-brown skin protects a tender interior that's gentler on the palate than storage onion varieties, making it especially valuable for gardeners in warm zones (2-9) who want fresh, everyday eating onions rather than keepers. This non-GMO hybrid grows 18-24 inches tall and suits greenhouse beds, garden plots, and raised beds equally well.
Photo © True Leaf Market
Growing Conditions
USDA Zone
2-9
Sunlight
Full Sun
Water
Moderate
Soil
Well-drained, Fertile Loam, Moderately Rich
Growth Stats
24 in
Height
Spacing
3
Plant Profile
Sunlight
Full Sun
Water
Moderate
Zones
2-9
Size
24in H x ?in W
Growth
—
Care
Moderate
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Highlights
The flattened globe shape and mild, sweet flavor distinguish this hybrid from typical storage onions, which tend toward sharper profiles. Bred specifically for short-day photoperiods, it performs where long-day varieties struggle, opening new growing possibilities in tropical and subtropical regions. The yellow-brown skin gives no hint of the gentle sweetness waiting inside, making it a surprising pleasure for those expecting a sharper bite.
Common Uses
Fresh eating is the primary strength of this variety. The mild, sweet character makes Superex ideal for slicing raw into salads, salsas, and fresh sauces where gentleness matters more than storage life. It works beautifully caramelized or roasted whole, where sweetness intensifies, and slices well into stir-fries and everyday cooking without the bite of storage onions.
Growing Timeline
No timeline data available yet for this variety.
Care Instructions
Start Indoors
Start seeds indoors 8-10 weeks before your last frost date in cooler zones, sowing at 70°F in seed-starting mix. Keep soil consistently moist until germination occurs at 7-14 days. Transplant seedlings into containers when they develop true leaves, maintaining warmth and bright light to prevent leggy growth.
Transplant Outdoors
Harden off seedlings over 7-10 days by gradually exposing them to outdoor conditions. Transplant when 4-6 inches tall into garden beds or raised beds after last frost, spacing 3 inches apart in rows 15 inches apart. Plant at the same depth they were growing indoors, firming soil gently around the base.
Direct Sow
Direct sow seeds 1/4 inch deep in garden soil or raised beds after last frost, thinning seedlings to 3-inch spacing once they're 2-3 inches tall.
Harvesting
Superex reaches maturity in 160 days. Harvest when foliage yellows and begins to fall over, typically mid to late summer in temperate zones. Gently dig bulbs from the soil and allow them to cure in a warm, dry, well-ventilated area for one to two weeks before storing, which helps dry the outer skin and extends shelf life slightly. The bulb is ready when the neck feels papery and dry to the touch.
Growing Calendar
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Companion Planting
Pests & Diseases
Ecology & Traits
Edible
Scientific Classification
Allium cepa
Family
Amaryllidaceae
Genus
Allium
Native Status
L48 (I)