Onions are an essential ingredient in most of the dishes from an organic garden — and fortunately easy to grow. Even a beginner gardener can get a good harvest from sets. 🧅
When to plant?
| Method | Planting | Harvest |
|---|---|---|
| Sets (spring) | March–April | July–August |
| Sets (autumn) | September | May–June (early!) |
Planting and care
- Plant spacing: 10-12 cm, row spacing: 25-30 cm
- The tip of the set should barely be below soil level
- Weeding is essential — onions can’t compete with weeds
- Watering: generous while bulbs are developing, stop 3-4 weeks before harvest
Harvest and storage
- Sign: two-thirds of the foliage has yellowed and fallen over
- Harvest in dry weather and let them dry in the sun for 1-2 weeks
- Storage: dry, airy, 0-5°C — keeps for 6-8 months!
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Summary
Onions: easy from sets, gentle watering during bulb formation, harvest in dry weather, dry in the sun. Autumn sets get you early spring onions too! 🧅
- Why is it so important to stop watering onions 3-4 weeks before harvest?
Onion storage life depends mainly on the outer, paper-like skin layers drying out properly, which can only happen fully once the soil no longer holds excess moisture. If watering isn’t stopped in time, the bulb stays wetter at harvest, which weakens how well the skin adheres and significantly shortens storage life, since damp tissue is a breeding ground for rot-causing fungi.
- Why does the foliage falling over signal exactly the right time to harvest, and what’s happening inside the plant then?
Foliage falling over signals that the plant has finished moving nutrients from the leaves into the bulb, and the tissue at the base of the neck naturally weakens, causing the tops to topple. If left in the ground past this point, the bulb gains no further nutritional value, but becomes exposed to soil pathogens and excess moisture, which would reduce its quality.
- Why does freshly harvested onion need to dry in the sun for 1-2 weeks before storage?
During drying (also called “curing”), the outer layers of the onion become papery, thin and tightly sealed, forming a natural protective layer around the edible interior. Without this process the skin would stay loose and moisture-absorbing, leading to rapid mould and rot within just a few weeks of storage instead of the onion keeping for months.
- Why bother with autumn sets planted in September when spring planting is already an option?
Autumn-planted sets already root and develop some foliage before winter halts growth, giving them a significant head start over spring sets and allowing harvest as much as 1-2 months earlier. This early onion crop is especially valuable because it bridges the gap between when last year’s stored onions run out and this year’s spring-planted crop matures.