Onion 'Eclipse' Growing Guide: From Seed to Harvest
By The Diggers Club - Australia's No.1 Gardening Club | Published: 2026-10-21
Category: How-to Guides
Learn how to grow Onion 'Eclipse' from seed to harvest, including sowing, spacing, and when to pick for the best flavor.
Quick Answer
To grow Onion 'Eclipse' successfully, sow seeds in late winter to early spring, provide well-drained soil and full sun, and harvest when the tops fall over for the sweetest, mildest bulbs.
Why Choose Onion 'Eclipse'?
Onion 'Eclipse' is a heirloom white onion that thrives in southern climates with long growing seasons. It's particularly good for producing mini or pearl onions in cooler regions, making it a flexible choice for gardeners who want variety in the kitchen.
The bulbs are round, crisp, and mild-flavoured, perfect for fresh eating or bunching. Because it's easy to grow in raised beds or containers, it suits both new and experienced gardeners.
Understanding Day Length and Climate
Onions are sensitive to day length, which triggers bulb formation. 'Eclipse' is described as ideal for southern climates and long growing seasons, suggesting it behaves like a long-day onion. In Australia, this means it's best suited to southern regions where summer days are longer. Gardeners in northern areas may find that bulbing is delayed or less uniform.
If you're unsure about your local conditions, check with your regional gardening group or use a local planting calendar to time your sowing.
Step-by-Step Growing Guide
- Sow seeds at the right time: In southern Australia, sow seeds in late winter to early spring (August to September) to take advantage of the long growing season. Use seed trays or direct sow into well-drained soil. Check your local frost dates; 'Eclipse' can handle cool weather but avoid frost after germination.
- Prepare the soil properly: Onions need weed-free, well-drained soil. Work in compost before planting, and ensure the soil is loose to a depth of about 15 cm. Avoid fresh manure, which can cause lush tops but poor bulbs. Do a simple drainage test: if water pools after rain, add organic matter or use raised beds.
- Transplant or thin seedlings: When seedlings are about 10 cm tall, transplant them or thin to 5-8 cm apart. 'Eclipse' thrives with shallow spacing, so don't bury the bulbs—keep the base at soil level. Crowding is a common mistake; give each onion enough room to form a full bulb.
- Water consistently, but not too much: Keep the soil evenly moist, especially during bulb formation. Reduce watering once the tops start to yellow, as too much moisture can cause rot. Use a moisture meter or check the top 2 cm of soil—if dry, water deeply.
- Feed lightly for healthy growth: Apply a balanced fertilizer at transplanting and again when bulbs begin to swell. Avoid high-nitrogen feeds late in the season, which encourage leaf growth over bulbs. If you see thick necks, cut back on nitrogen and let the plant mature naturally.
- Harvest at the right time: Harvest when the tops fall over and begin to dry. Gently lift bulbs with a fork and leave them to cure in a dry, airy place for a couple of weeks before storing. Don't wait too long after tops fall—over-mature bulbs can split or rot.
Onion 'Eclipse' at a Glance
- Onion 'Eclipse': Heirloom white onion ideal for southern climates and long growing seasons; great for mini or pearl onions in cooler regions. This tells you where and when to plant: choose a spot with long daylight hours and cool summers to get the best bulb formation.
Onion 'Eclipse' - Onion 'Eclipse': Forms round, crisp, mild-flavoured bulbs—perfect for bunching or fresh use. You can harvest some as green onions early and let others mature, giving you two crops from one sowing.
