Superstar Onion is a reliable bulbing onion that reaches maturity in 85 to 90 days, thriving across hardiness zones 3 through 10. This cultivar grows best in slightly acidic to neutral soil (pH 6.0 to 7.0) and demands consistent moisture throughout its season. From direct seeding to harvest, Superstar delivers the straightforward growing experience home gardeners need, producing full-sized bulbs that store well through winter.
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High
3-10
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Moderate
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Superstar Onion matures quickly, reaching harvest size in under three months from seed. Its broad hardiness range means gardeners in cold northern regions and warm southern zones can both succeed. The variety responds well to thinning and transplanting, with source catalogs recommending careful seedling separation for maximum bulb development, and it forms protective papery skin that makes it excellent for storage after proper curing.
Superstar Onion is grown for its edible bulbs, which can be harvested at various stages. Young plants thinned to pencil size work as scallions, while mature bulbs offer full-sized onions for cooking, raw use in salads, and storage for later use.
No timeline data available yet for this variety.
Sow 10 to 12 seeds in a 4- to 6-inch pot. Keep soil at 50 to 70 degrees Fahrenheit for germination. If seedling tops exceed 5 inches before transplanting, cut them back to 3 inches to maintain vigor.
When seedlings reach 4 to 5 inches tall, thin to the strongest plant or carefully separate multiple seedlings for transplanting. Place seedlings in a shallow trench, fill around them with soil, and water in thoroughly. Space plants 2 inches apart with rows 12 inches apart.
Direct seed outdoors once soil is workable and temperatures reach 50 to 70 degrees Fahrenheit. Thin seedlings to the strongest plant when they reach 4 to 5 inches tall. Days to maturity are calculated from the date of direct seeding.
For scallion harvest, pick when plants reach pencil size or larger, wash well, and trim the roots. For full-sized bulbs, harvest after about half the tops have naturally fallen over. Push over any remaining upright tops and wait approximately one week before harvesting. Loosen soil around bulbs a few days before harvest to encourage drying. Always harvest in dry weather, as moisture promotes rot and prevents proper curing. Remove any bulbs that have sent up flower stalks, as these will not store as well.
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