The Ailsa Craig onion is considered a long day onion- (Long-day onions need about 14 to 15 hours of daylight to bulb. Short-day onions need 10 hours of daylight).  The Ailsa Craig onion is named after Ailsa, a small round island off the coast of Scotland that is solid rock.  Ailsa Craig is a globe-shaped onion, solid, and can achieve 20cm (8”) in diameter.  They are large straw-colored onions with small necks that can average 0.9 -2.2 kg (2-5 pounds) each.  They are best for fresh use, not extended storage.  Start seeds indoors as early as you can just to ensure that you have the biggest transplants available for spring planting. 

Growing Instructions:

Onions can be grown from seeds, sets, or transplants. If starting from seeds, start them indoors 8-10 weeks before the last expected frost date in your area. Transplants can also be purchased from a nursery or garden center. Onions prefer a sunny location and well-drained soil that is rich in organic matter. Soil pH should be between 6.0 and 7.5. If planting sets or transplants, space them 10-15cm (4-6”) apart in rows spaced 30cm (12”) apart. If planting seeds, sow them 1cm (½”) deep and 2.5-5cm (1-2”) apart in rows spaced 30cm (12”) apart.

Keep the soil moist but not waterlogged during the growing season. Onions prefer consistent watering throughout the season. Fertilize with a nitrogen-rich fertilizer every 3-4 weeks during the growing season. Onions are ready for harvest when the leaves turn yellow and start to fall over. Carefully lift the onions out of the soil and lay them out in a dry, well-ventilated area to cure for 1-2 weeks before storing.