How to Grow Ailsa Craig
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Ailsa Craig
Allium cepa 'Ailsa Craig'
vegetableAilsa Craig is a large, golden-yellow onion variety known for its mild, sweet flavor and exceptional storage qualities. Originating from Scotland, it produces globe-shaped bulbs that can weigh 1-2 pounds each when grown under ideal conditions. This heirloom variety is prized by gardeners for its reliability, productivity, and excellent keeping ability.
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Example Ailsa Craig timeline · Pittsburgh, PA (Zone 6b)
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Plant Ailsa Craig
Around Apr 17Near Pittsburgh's average last spring frost.
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Tend & protect
Late spring–summerWatering, feeding, and pest-watch reminders.
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Harvest Ailsa Craig
Around Aug 5≈ 110 days after planting
Sample dates for Pittsburgh, PA. Sign up to get exact Ailsa Craig dates for your own zip code.
Growing Conditions
Soil
Growing Zones
Find your zone →Thrives in zones 4-8, but can be grown successfully in zones 3-9
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Get my Ailsa Craig timeline →Growth Stages
Seedling
2-3 weeksThin, grass-like green shoots emerge from soil; very delicate appearance
Keep soil consistently moist but not waterlogged; provide bright light; thin seedlings to proper spacing once they develop true leaves
Vegetative Growth
6-8 weeksMultiple green shoots form, resembling bunching onions; root system develops underground
Maintain consistent moisture and fertility; apply balanced fertilizer every 3-4 weeks; thin to final spacing if needed; keep area weed-free
Bulb Development
4-6 weeksBase of plant begins to swell as bulb forms; foliage remains green and vigorous
Continue regular watering; reduce nitrogen to avoid excessive leaf growth; ensure adequate potassium for bulb size; maintain consistent soil moisture
Maturation
2-3 weeksFoliage yellows and begins to fall over; bulb reaches full size with papery brown outer skin developing
Gradually reduce watering as tops yellow; do not water once tops have fallen; allow plants to cure in ground for 1-2 weeks before harvest
Harvest & Curing
2-4 weeks curingTops are completely dried and brown; bulbs can be pulled and should cure in a warm, well-ventilated location
Pull bulbs gently when soil is slightly moist; cure in single layer in shade for 2-3 weeks; store in cool (50-60°F), dry location with good air circulation
Companion Planting
Plan your garden →Plant with:
Avoid planting near:
Common Pests
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Use row covers on seedlings; rotate crops yearly; remove infested bulbs; encourage beneficial parasitic wasps
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Spray with insecticidal soap or neem oil; maintain adequate moisture; remove heavily infested plants; use reflective mulches
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Apply diatomaceous earth around base; use row covers early season; practice crop rotation; remove and destroy affected bulbs
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Increase humidity with regular misting; spray with water to dislodge; use sulfur or miticide if severe
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and
Hand-pick at dusk; use beer traps; apply copper tape or diatomaceous earth barriers; encourage ground beetles
Uses
Sweet Eating & Storage
CulinaryAilsa Craig onions are renowned for their mild, sweet flavor and low pungency, making them excellent for fresh eating, caramelizing, and long-term storage. Their large size and thin skins are ideal for grilling, roasting, and making onion rings. [source]
Pickling & Preserving
CulinaryThe firm, compact flesh of Ailsa Craig onions makes them particularly suited to pickling and preservation. They hold their shape well when cooked and can be preserved by canning, freezing, or pickling for year-round use. [source]
Kitchen Storage
HouseholdAilsa Craig's exceptional storage longevity means you can enjoy fresh onions from your garden throughout winter and into spring with proper curing and storage conditions. This makes it ideal for gardeners seeking food security and year-round pantry supplies. [source]
Exhibition & Competition
CraftAilsa Craig is a traditional show onion and winner of the Royal Horticultural Society Award of Garden Merit. Its large, attractive golden bulbs and consistent size make it popular for agricultural fairs and vegetable competitions. [source]
Traditional Health Uses
MedicinalLike all onions, Ailsa Craig contains quercetin and other polyphenols with potential anti-inflammatory and antioxidant properties. Traditionally used in various cuisines and folk medicine for digestive and immune support. [source]
This is not medical advice. LizPlants is not a medical resource. Always consult a qualified healthcare professional before using plants medicinally.
Harvest Tips
Harvest when 50-75% of foliage has yellowed and fallen over, typically mid-summer in most zones. Gently loosen soil with a fork and pull bulbs carefully to avoid bruising. Cure in a warm (70-75°F), dry, well-ventilated location for 2-3 weeks until necks are completely dry and papery. Store in mesh bags or net at 50-60°F with 60-70% humidity; under proper conditions, Ailsa Craig can store 6-8 months.
Fun Facts
- 🌱 Ailsa Craig is named after a small rocky island off the coast of Scotland (Ailsa Craig), where it was developed in the late 1800s. It is one of Scotland's greatest contributions to heirloom vegetable varieties.
- 🌱 This variety was created by Scottish seed company Thompson & Morgan and won the Royal Horticultural Society's Award of Garden Merit, a distinction it maintains to this day.
- 🌱 Under optimal growing conditions with long daylight hours (14+ hours), Ailsa Craig can produce individual onions weighing 2-3 pounds, making it one of the largest-bulbing onion varieties available to home gardeners.
Gardening Terms
New to gardening? Learn about terms used in this guide:
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