Onion sets are small bulbs grown from seeds, which enter dormancy very early (while still in the juvenile phase) due to the cultivation method. They typically range in diameter from 9 to 23 mm and are cultivated under the supervision of agricultural seed specialists to ensure the authenticity and purity of the cultivar, as well as the health status of this planting material, in accordance with agricultural seed laws. Onion sets are intended for either autumn or spring planting.
Onion seeds intended for the production of sets are sown at a very high density (700 – 1500 plants/m², using 10 – 12 g of seeds/m²). This limited vegetative space forces the plant to produce bulbs earlier and mature sooner.
Soil preparation, sowing time, and crop care measures are the same as those used for onions grown from direct seeding. Cultivars intended for pickling are grown in a similar manner.