Sets are less demanding than seed grown onions which require fine textured soil and a high organic matter.
Dig the bed over in winter, adding compost and lime if necessary. Firm the surface before planting, and add a general fertiliser. Plant in rows which are 30 cm apart and space the sets in the rows 12 cm. Push gently into the soft earth, and allow the tip to just show above the soil level. Firm soil around planted sets.