Growing onions from seed is more time-consuming than planting onion sets, which is common practice. Those who still do the work will be rewarded with small but firm tubers that store better and shoot less than onion sets.
Preparation of the soil and seeds
The soil for sowing onions should be loose and not freshly fertilized, since onions are weak consumers and react to over-fertilization with growth problems and diseases. It is important that the beds are thoroughly freed from weeds, otherwise the young plants will not grow. For spring sowing, the soil should already be dug up with organic fertilizer in the fall. Later fertilize with potash at most, e.g. B. with wood ash.
Good germination can usually be assumed for seeds purchased from specialist retailers. In the case of self-harvested seeds, it is advisable to check them for germination before sowing. For this, the seeds are placed in a glass of water, with the healthy seeds sinking to the bottom while the "empty" seeds remain on the surface. If you wish, you can use a seed bath with Humofix before sowing.
The Sowing
The right time depends on the weather. Since the onions germinate at relatively low temperatures, sowing can begin as early as February. However, the soil should be sufficiently dry. This is usually the end of March-beginning of April. The onion seeds can also be grown in the greenhouse, cold frame or in a cool, bright room and later transplanted outdoors.
- Sowing depth about 1 cm
- Row spacing approx. 20-25 cm
- isolated to 5-10 cm depending on the variety
- Germination temperature 15-18° C
- Germination time 3-4 weeks
tips and tricks
Given the relatively long germination time of the onion, it can be helpful to mark the rows by using the onion seeds together with fast-germinating seeds, such as e.g. B. Sow lettuce or radishes. It is also easier to identify and remove weed competition in the beds.