Heirloom
Meet the gentle giant of the onion world. Ailsa Craig traces its impressive lineage back to 1887 Scotland, where David Murray, gardener for the Marquis of Ailsa, first introduced this globe-shaped wonder at Culzean Castle. These pale yellow beauties routinely reach 1-2 pounds each, with some specimens tipping the scales at an astounding 5-6 pounds. At 110 days from transplant, this long-day variety rewards northern gardeners with mild, sweet flesh perfect for fresh eating.
Full Sun
High
3-10
18in H x 6in W
Annual, Perennial
High
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This Scottish heirloom transforms from humble seed to colossal bulb, creating onions so large they become conversation pieces in the garden. The pale yellow skin conceals remarkably mild, sweet flesh that makes these giants ideal for fresh preparation rather than long-term storage. Originally cultivated in the gardens of Scottish nobility, Ailsa Craig has maintained its reputation for spectacular size and gentle flavor for over 135 years. Northern gardeners particularly treasure this long-day variety, as it requires those extended summer days of 14-16 hours to reach its full magnificent potential.
These massive mild onions excel in fresh preparations where their sweet, gentle flavor can shine without the harsh bite of storage varieties. Their substantial size makes them perfect for stuffing, grilling whole, or slicing into thick rings for sandwiches and burgers. The mild flesh caramelizes beautifully when cooked, developing rich sweetness that enhances soups, stews, and roasted dishes without overwhelming other flavors.
Sow seeds indoors 10-12 weeks before the last frost date, planting 1/4 inch deep in seed-starting trays. Maintain temperatures around 60°F for germination in 7-14 days. Sow up to 10-12 seeds per 4-6 inch pot, and if tops reach over 5 inches before transplant time, trim them back to 3 inches.
Transplant hardened seedlings 4-6 weeks before the last frost, as these can tolerate light frosts. Carefully separate seedlings and plant in shallow trenches, then fill soil around them and water thoroughly. Gradual acclimation before transplanting ensures stocky, resilient plants.
Begin reducing water as bulbs approach maturity to allow protective paper skin to form. When about half the tops have fallen over naturally, push over the remaining tops and wait approximately one week before harvesting. Cure the bulbs in a warm (75-80°F), shaded, well-ventilated location for 2-4 weeks until the outer skin and necks are completely dry, then trim tops to one inch above the bulb.
Unruly tops may be clipped to 5 inches at transplant time to encourage root establishment. As harvest approaches and about half the tops have naturally fallen over, push down the remaining tops and wait about one week before harvesting.
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“In 1887, David Murray, head gardener for the Marquis of Ailsa at the magnificent Culzean Castle in Maybole, South Ayrshire, Scotland, introduced what would become one of the most celebrated giant onions in gardening history. Named for the rocky island of Ailsa Craig that sits in the Firth of Clyde, this remarkable cultivar emerged from the skilled hands of a Scottish castle gardener who understood how to coax extraordinary size from ordinary alliums. The variety has traveled far from its noble Scottish origins, carrying with it the legacy of Victorian garden craftsmanship and the pursuit of horticultural excellence that defined the great estate gardens of the era.”