Kings Seeds (Onion Sets)

https://www.kingsseeds.com/Products/Vegetable-Seeds/Onion-Sets

Onion sets are small bulbs that have been harvested prematurely, to be planted and then grow into full-size onions.

Our onion sets are supplied as 500g nets which equals approximately 50 bulbs, depending on the variety. We have autumn planting, and spring planting onion sets available at certain times throughout the year.

Simply Seed

https://www.simplyseed.co.uk/onion-sets.html

Onion Sets can be conveniently sown either in the Autumn or in the Spring with different varieties best suitable for planting at each time of year. For an early harvest, Autumn planted sets are planted when other vegetables in the crop rotation have vacated their plots and are then overwintered in the soil. As soon as Spring arrives they will grow rapidly and can then be harvested at any time during the early summer.

D T Brown (Onion Sets and Shallots )

https://www.dtbrownseeds.co.uk/Onions-Garlic-1/

The best performing vegetable seed varieties for the home gardener! We work closely with seed breeders around the world to bring you the very best varieties for growing on your allotment or vegetable patch. Every year we conduct extensive trials on our own plot and new varieties are scored and selected based upon their taste, garden performance, yield and resistance to pest and diseases.