Onion
Seed # 102
Basic Information
- Seed Number
- 102
- Seed Name
- Onion
- Variety
- Ailsa Craig
- Category
- Vegetable
- Plant Family
- Amaryllidaceae
- Plant Type
- Long-day bulbing onion (Allium cepa)
- Planting Method
- Direct Sow or Transplant
- Seed Status
- In Seed Bank
- Created
- 2026-08-14 00:50:34
- Updated
- 2026-08-19 15:35:29
Planting Information
- Start Planting Date
- Mar 10
- Last Recommended Planting Date
- May 15
- Plantable Months
- March, April, May
- Indoor Start
- Mar 10 – Mar 24
- Direct Sow
- Apr 1 – Apr 30
- Transplant
- Apr 15 – May 15
- Indoor Start Weeks Before Frost
- 8 weeks
- Transplant Weeks After Frost
- Not recorded
- Germination Days
- 7–14 days
- Harvest/Maturity
- 105 days from direct seeding; approximately 10-15 days less from transplant
- Succession Planting
- Not recorded
Growing Conditions
- Ideal Soil Temperature
- 55-75°F
- Planting Depth
- 1/4 in
- Plant Spacing
- 4-6 in
- Row Spacing
- 12-18 in
- Thin-To Spacing
- 4-6 in
- Sun Requirements
- Full sun
- Water Needs
- About 1 in/week; keep evenly moist during growth and bulbing; reduce irrigation as tops mature
- Soil Preference
- Fertile, loose, well-drained soil high in organic matter; approximately pH 6.0-7.0
- Minimum Container Size
- 10-12 in deep
- Plant Height
- 12-24 in foliage
- Perennial/Biennial Status
- Biennial
- Container Friendly
- Yes
- Trellis/Support Needed
- No
- Frost Tolerant
- Yes
- Heat Tolerant
- No
- Drought Tolerant
- No
- Pollinator Friendly
- Yes
- Medicinal
- No
Garden Uses
Container Culinary Medicinal Pollinator Seed SavingCompanion Planting
| Plant | Relationship | Notes |
|---|---|---|
| Arugula | Good Companion | Not recorded |
| Broccoli | Good Companion | Not recorded |
| Brussel Sprouts | Good Companion | Not recorded |
| Cabbage | Good Companion | Not recorded |
| Carrots | Good Companion | Not recorded |
| Carrots | Good Companion | Not recorded |
| Lettuce | Good Companion | Not recorded |
| Lettuce | Good Companion | Not recorded |
| Lettuce | Good Companion | Not recorded |
| Pepper | Good Companion | Not recorded |
| Pepper | Good Companion | Not recorded |
| Pepper | Good Companion | Not recorded |
| Pepper | Good Companion | Not recorded |
| Pepper | Good Companion | Not recorded |
| Pepper | Good Companion | Not recorded |
| Pepper | Good Companion | Not recorded |
| Pepper | Good Companion | Not recorded |
| Pepper | Good Companion | Not recorded |
| Radish | Good Companion | Not recorded |
| Radish | Good Companion | Not recorded |
| Radish | Good Companion | Not recorded |
| Radish | Good Companion | Not recorded |
| Tomato | Good Companion | Not recorded |
| Tomato | Good Companion | Not recorded |
| Tomato | Good Companion | Not recorded |
| Tomato | Good Companion | Not recorded |
| Tomato | Good Companion | Not recorded |
| Beans | Avoid | Not recorded |
| Beans | Avoid | Not recorded |
| Beans | Avoid | Not recorded |
| Beans | Avoid | Not recorded |
| Beans | Avoid | Not recorded |
| Beans | Avoid | Not recorded |
| Beans | Avoid | Not recorded |
| Beans | Avoid | Not recorded |
| Beans | Avoid | Not recorded |
| Beans | Avoid | Not recorded |
| Beans | Avoid | Not recorded |
| Peas | Avoid | Not recorded |
| Peas | Avoid | Not recorded |
| Peas | Avoid | Not recorded |
Storage
- Seed Source/Brand
- MSU Extension; Detroit frost dates; Almanac Detroit
- Packet Year
- Not recorded
- Quantity Notes
- Not recorded
- Purchase Date
- Not recorded
- Expiration Year
- Not recorded
- Storage Box
- Not recorded
- Container
- Not recorded
- Envelope
- Not recorded
- Row
- Not recorded
- Slot
- Not recorded
- Storage Notes
- Not recorded
Notes
Original Planting Method: Start indoors or direct sow bunching types
Outdoor / Direct Sow / Transplant Window: Apr 1 – May 15; Aug 15 – Sep 10 for bunching onions
Days to Harvest / Bloom: 60–120 days
Pollinator Friendly: Flowers support pollinators if allowed to bloom
Medicinal / Herbal Use: Culinary/medicinal tradition
Succession / Reusable Notes: Bulbing onions need an early start; bunching onions are more flexible.
Zone 6B Notes: Ailsa Craig is a long-day onion; start early indoors for best bulbs.
Companion Plants: Carrots, tomatoes, peppers, lettuce, brassicas, strawberries, chamomile, beets
Avoid Planting Near / Watch Outs: Beans, peas
Sources: MSU Extension: https://www.canr.msu.edu/resources/garden_planning_calendar | Detroit frost dates: https://www.ufseeds.com/vegetable-planting-calendar-detroit-michigan.html | Almanac Detroit: https://www.almanac.com/gardening/planting-calendar/MI/Detroit
[[RESEARCH ENRICHMENT START]]
Zone 6B: Ailsa Craig is a long-day onion well adapted to Michigan latitude. Starting seedlings indoors is preferred for maximum bulb size because plants need substantial leaf growth before long summer days trigger bulbing.
Germination: Start 6-8 weeks before the last frost. Cover seed approximately 1/4 inch deep. Onion seedlings tolerate cool conditions once established.
Harvest: Harvest after tops begin to fall naturally and bulbs have reached full size. Cure in a warm, dry, ventilated area before storage. Ailsa Craig is prized more for size and mild sweetness than long storage.
Seed Saving: Onions are biennial and require overwintering or vernalization to flower. Allium cepa varieties cross readily through insect pollination, so substantial isolation is required for pure seed.
Special Care: Ailsa Craig can produce extremely large bulbs with wide spacing, rich soil and steady moisture. It is a long-day variety suited to northern regions.
Research Source: Johnny's Selected Seeds — https://www.johnnyseeds.com/vegetables/onions/full-size-onions/ailsa-craig-organic-onion-seed-485G.html — long-day adaptation, 6-8 week indoor start, 1/4-inch depth, 4-6 inch transplant spacing, 12-18 inch rows and maturity qualifier
Research Source: High Mowing Organic Seeds — https://www.highmowingseeds.com/organic-non-gmo-ailsa-craig-onion.html — 105-day maturity
Research Source: Territorial Seed Company — https://territorialseed.com/products/onion-ailsa-craig — long-day classification, 105-day maturity, large bulb size and sweet flavor
[[RESEARCH ENRICHMENT END]]