Type
long-day sweet heirloom
Onion variety
Ailsa Craig Onion
A famous exhibition onion capable of very large size with mild flavor. It is best used fresh rather than stored long term.
Days to maturity
95 to 110
Best for
large bulbs, slicing
About Ailsa Craig
Ailsa Craig is a long-day heirloom onion famous for producing very large, round, straw-colored bulbs, and it is often grown for exhibition size. The flesh is mild and sweet, and under ideal conditions individual bulbs can reach impressive weights. It is grown more for size and fresh eating than for long keeping.
Growing Ailsa Craig Onion
To reach show size, start seed very early indoors and set out well-spaced transplants, giving each plant 6 or more inches and consistently rich, moist soil. A long season and steady feeding are key, since it needs many weeks to bulk up. It is a poor keeper, so harvest when the tops fall over and use the large bulbs fresh rather than storing them.
Full growing guide
For planting dates, care, and harvest that apply to all onions, see the complete guide.
How to grow OnionsOther onions varieties
Variety characteristics are general guidance for US home gardens; performance varies by climate, soil, and season. Seed and plant availability differs by supplier. Page updated Aug 4, 2026.