Probably only a few hobby gardeners want to propagate onions themselves. Finally, seeds and onion sets are available in abundance at affordable prices. If you're ambitious, you'll be able to do it with these instructions.
How do I propagate onions in my own garden?
To propagate onions yourself, first harvest the seeds from inflorescences, sow them densely and harvest the resulting onion sets. Store onion sets in a cool, dark place before planting them in the garden in spring and harvesting them in autumn.
There are two ways to propagate onions yourself. The first option is to grow onion sets from purchased seeds and plant them in the spring of the second year in order to harvest large onions in the fall. The second option requires more effort and takes a longer gardening season.
You harvest the seeds in the first year, the onion sets the following year, which can grow into large tubers in the third year. The individual steps are described below. If you want to try out the simpler option first, please start with step 2.
1. Step: Harvest seeds
As the young bulb plants grow, some of them form inflorescences. Normally this bolting is not desirable because the flower develops on such plants instead of the tuber. However, if you allow the plant to bloom, the flower will later form a seed capsule from which the seeds can be harvested. These can germinate for approx. 3 years.
Then proceed as follows:
- harvest the onion with the inflorescence in autumn like all other onions
- Hang these upside down to dry out, if necessary tying a paper bag over the inflorescence
- store the dried inflorescences in a cool, dark place until next spring
- Store the inflorescences at temperatures of 25-35 °C one month before sowing
2. Step: Harvest onion sets
The home-grown seeds are sown so densely that hazelnut-sized bulbs can develop from them. Once they have reached the desired size, harvest the onion sets and let them dry well. They are stored cool over the winter and kept warm (25-35 °C) for about a month before cutting.
Tips & Tricks
To separate the good seeds from the bad ones, pour them into a glass of water. The shells and the “empty” seeds remain on the surface, while the good seeds sit on the bottom of the glass.
