Gardeners Almanac

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Onions

Garden Vegetables

How to Grow Onions in Your Home Garden: A Flavorful Essential

Onions are a staple in the kitchen and surprisingly easy to grow in Canadian gardens. They store well, are incredibly versatile, and offer a high yield in a small space.

Why Grow Onions?

  • Long shelf life: Stores well for months.

  • Essential flavor: Used in countless recipes.

  • Cold-tolerant: Thrives in cooler spring climates.

  • Easy to grow: Ideal for beginners.

Best Onion Varieties for Canadian Gardens

  • Yellow Globe: Long-storing and widely adapted.

  • Red Baron: Mild flavor, great for fresh use.

  • Walla Walla: Large, sweet, early-maturing.

  • Sturon: Great for cool climates, excellent storage.

Soil Requirements

  • Type: Loose, well-drained, fertile soil.

  • pH: 6.0–7.0.

  • Fertility: High; amend with compost or all-purpose fertilizer.

Avoid compacted or heavy clay soils.

Sunlight & Temperature

  • Sun: Full sun (6–8 hours daily).

  • Temperature: Ideal range: 13–24°C (55–75°F).

  • Frost Tolerance: Moderate; hardy seedlings.

Planting Guidelines

  • Start indoors (seeds): 10–12 weeks before last frost.

  • Sets/transplants: Plant in late April to early May.

  • Spacing:

    • In-row: 3–4 inches apart.

    • Rows: 12–18 inches apart.

  • Depth: 1/2 inch deep.

Choose between growing from seeds, sets (small bulbs), or seedlings.

Watering & Feeding

  • Watering: 1 inch/week, evenly throughout the season.

  • Feeding: High phosphorus for roots, nitrogen early on.

  • Mulch: Helps retain moisture and suppress weeds.

Yield Per Square Foot

  • Per square foot: 9–16 onions, depending on spacing.

Bulbs size up best with good spacing and weeding.

Common Pests & Diseases

  • Pests: Onion maggots, thrips.

  • Diseases: Downy mildew, botrytis rot.

  • Prevention: Rotate crops, avoid overwatering, use row covers.

Harvesting Tips

  • Harvest when tops fall over and begin to yellow.

  • Gently pull bulbs and cure in a warm, dry place for 2–3 weeks.

  • Trim tops and roots for storage.

Storage Tips

  • Store in mesh bags in a cool, dry, dark place.

  • Sweet onions: shorter shelf life; eat first.

  • Keep well-ventilated to prevent rot.

Container Growing

  • Use 10–12 inch deep containers.

  • Choose bunching or small-bulb varieties.

  • Water frequently and fertilize regularly.

Enjoying Your Onions

  • Use fresh in salads, salsas, or sandwiches.

  • Caramelize, grill, roast, or pickle.

  • Add depth to soups, stews, and sauces.

🌿 Onion Planting Calendar (Southern Canada)

Task Timeline Notes
Start seeds indoors Late Jan to early Feb For long-day onions
Transplant sets/seeds Late April to early May Plant in full sun
Thin seedlings May Leave 3–4 inches between plants
Harvest bulbs Late July to early Sept After tops yellow and fall
Cure & store 2–3 weeks post-harvest Warm, dry, ventilated space

Onion Planting Diagram

 Raised Bed Layout (4 ft x 4 ft)

 +-----------------------------+
 | o o o o o o o o o o         |  o = Onion (4 in. apart)
 | o o o o o o o o o o         |
 | o o o o o o o o o o         |
 +-----------------------------+

Container Setup:

  • Use well-drained potting mix.

  • Water consistently.

  • Feed every 2–3 weeks.

🧅 Companion Chart: Onions vs. Garlic vs. Leeks

Feature Onions Garlic Leeks
Days to Harvest 90–120 days 210–240 days 120–150 days
Yield per sq. ft. 9–16 bulbs 4–9 bulbs 4–6 leeks
Growth Habit Bulb-forming Bulb-forming Tall stems
Best Planting Time Early spring Fall (hardneck) Early spring
Storage Longevity 2–6 months 6–12 months 1–2 months
Container Friendly Yes Yes (small varieties) Yes
Common Uses Raw, cooked, dried Roasted, sauces Soups, stews, sautés

 

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