Water Needs: Moderate watering is required. Keep the soil consistently moist, especially during the early stages of growth, but avoid waterlogging to prevent bulb rot. Water deeply but infrequently, allowing the soil to dry slightly between watering.
Sunlight Needs: Full sun is essential (6-8 hours of direct sunlight daily). Red onions require plenty of sunlight to develop strong bulbs and vibrant color.
Time to Germinate: 7-10 days.
Seed Soaking: Soaking seeds overnight is optional but can help speed up germination.
Tray/Pot Recommendations: Start seeds in seed trays or small pots and transplant them into the garden when they are 10-15 centimeters tall. Alternatively, direct sowing into the garden is also effective. Ensure good drainage in containers if using pots.
Space Requirements: Space plants 10-15 centimeters apart in rows 30 centimeters apart. Red onions need enough space to develop healthy bulbs, so ensure they are not overcrowded.
Temperature Requirements: Optimal growing temperatures range from 15-25°C. Red onions thrive in cooler conditions but can tolerate warmer climates during the growing season.
Best Growing Season: In Thailand, red onions are best grown from October to March, during the cooler months, to avoid the excessive heat that can hinder bulb formation.
Time to Harvest: 90-120 days from planting. Harvest when the tops begin to yellow and fall over. Allow the bulbs to cure in a dry, airy place for several days before storage.
