Onions | Allium

Read the Seed Guide for Annual / Biennials: https://bloomoutlet.com/planting-guide-for-annual-biennial-seeds/

ONIONS (Allium)

Seed Treatment

  1. Pre-Soaking for Faster Germination

    • Soak seeds in warm water (not hot) for 12–24 hours before planting.

    • This softens the seed coat and promotes quicker germination.

  2. Disinfection (To Prevent Fungal Issues)

    • Soak seeds in a mild hydrogen peroxide solution (1 part 3% hydrogen peroxide to 10 parts water) for 30 minutes.

    • Rinse thoroughly with clean water before planting.

Sowing Instructions

Indoor Sowing (Recommended for Early Start)

  1. Timing: Start seeds 8–10 weeks before the last frost date indoors.

  2. Container: Use seed trays or shallow containers filled with light, well-draining soil.

  3. Planting Depth: Sow seeds ¼ inch (6 mm) deep and lightly cover with soil.

  4. Moisture & Temperature: Keep soil moist but not soggy; maintain temperatures of 65–75°F (18–24°C).

  5. Light: Provide 12–16 hours of bright light per day (use grow lights if needed).

  6. Germination Time: 7–14 days under optimal conditions.

  7. Thinning: Once seedlings reach 3 inches (7–8 cm) tall, thin them to about ½ inch apart.

Direct Sowing (For Warmer Climates)

  1. Timing: Sow outdoors as soon as the soil is workable in early spring.

  2. Location: Choose a full-sun location with loose, well-drained, fertile soil.

  3. Planting Depth: Sow seeds ¼ inch deep, spaced ½ inch apart in rows 12–18 inches apart.

  4. Watering: Keep soil evenly moist but avoid overwatering.

  5. Thinning: Once seedlings reach 3 inches tall, thin to 2–4 inches apart for proper bulb development.

Growing & Care Tips

  • Fertilization: Use a high-nitrogen fertilizer every few weeks until bulbs start forming.

  • Mulching: Apply a thin layer of straw or compost to retain moisture and suppress weeds.

  • Watering: Provide 1 inch (2.5 cm) of water per week. Reduce watering as bulbs mature.

  • Harvesting: Harvest green onions when tops are 6–8 inches tall; for bulb onions, harvest when tops begin to fall over.

 

WHITE LISBON ONION

Common Name: White Lisbon Onion

Type: Biennial

Fruit Size: 1 in (25 mm)

Plant Height: 12-14 in (30-35 cm)

Plant Spread: 4 in (10 cm)

Other Info: 10 days at 70 F (21 C). 60 days (Spring). 110 days (Fall). Full Sun. 


WHITE SWEET SPANISH ONION

Botanical Name: Allium cepa 'White Sweet Spanish Onion'

Days to maturity: 110

Fruit Size: 1 lb (453 grams)

Sunlight requirements: Full Sun. Requires 14 or more hours of continuous daylight. 

Germination time: 10 days at 70 F (21 C)

Seed depth: 1 / 2 in ( 1.3 cm)

Plant spacing: 8 in ( 20 cm)

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