Bulb Onion Farming: A Practical Guide
Growing bulb onions isn’t rocket science, but it’s not just “plant and forget” either. From soil prep to harvest, getting it right means understanding a bit about timing, weather, and what the plant needs. Here’s a straightforward guide based on real-world practices.
- Choosing the Right Onion Variety
Start with what works in your climate:
Short-day onions: Best for southern, warmer areas (they need ~10-12 hours of daylight).
Long-day onions: Do well in northern regions (need 14-16 hours of daylight).
Intermediate-day: For areas in between.
Popular varieties:
Red Creole – good for warmer climates, stores well.
Texas Super Sweet – large bulbs, mild taste.
Yellow Granex – the “Vidalia” type, very sweet.
- Site Selection and Soil Prep
Location:
Needs full sun, no shade.
Good drainage is critical – onions hate wet feet.
Soil:
Loamy or sandy loam is ideal.
pH between 6.0–6.8. Slightly acidic is best.
Work in well-rotted manure or compost a few weeks before planting.
Pro tip: Raised beds or ridges can help prevent rot in wetter areas.
- Planting
You can start from seeds, transplants, or sets:
Seeds: Cheapest, but take longer (~100–130 days).
Transplants: Small onion plants started elsewhere – good middle ground.
Sets: Small bulbs from last season – fastest, but may bolt early.
Spacing:
4–6 inches apart in rows 12–18 inches apart.
Don’t bury them too deep – just enough to cover the roots and base.
- Watering and Feeding
Water:
Onions need consistent moisture, especially during bulb formation.
Rough rule: 1 inch of water per week.
Avoid overwatering late in the season to prevent rot.
Fertilizer:
Nitrogen is key early on (e.g., urea or compost tea).
Stop nitrogen-heavy feeds once bulbs start forming (you’ll notice the neck swelling).
Tip: Sidedress with phosphorus and potassium around the 4–5 leaf stage.
- Weeding and Pest Management
Weeds compete hard – onions don’t like fighting for nutrients.
Use mulch or shallow cultivation.
Hand weed near bulbs to avoid damage.
Pests:
Onion thrips: Tiny, but they stunt growth. Use neem oil or insecticidal soap.
Cutworms and maggots: Rotate crops and avoid planting where onions or garlic grew last season.
Diseases:
Downy mildew, pink root, white rot – prevent with crop rotation and well-drained soils.
- Bulb Development and Maturity
As onions grow, the bulbs push up and expose themselves – don’t cover them back with soil.
When about half the tops fall over naturally, it’s time to think about harvesting.
- Harvesting
Gently pull onions once tops are down and outer skins are papery.
Cure them in a dry, shaded, and airy spot for 2–3 weeks.
Once necks are fully dry, clip the tops and roots.
- Storage
Store in a cool, dry place – around 32–40°F is ideal.
Mesh bags or open crates work well.
Avoid storing near potatoes (they emit moisture and can cause spoilage).
Storage life:
Sweet onions: 1–2 months
Storage types (like Yellow Globe): up to 6–8 months
Final Tips
Rotate crops – avoid planting onions in the same spot more than once every 3–4 years.
Don’t over-fertilize late in the season – it can prevent proper curing.
Label your rows – especially if planting multiple varieties.
Click here to buy Onions farming book