Sow spring onions in drills as close as 10cm apart in well prepared, weed-free soil. Seeds can be 2-3cm apart in the row with no need to thin. For a very early crop seeds can be started indoors in January. Spring onions can be sown throughout the growing season. For a continuous supply of pencil-thick onions we recommend sowing every two weeks. They are ready for harvest six weeks after sowing.