Sowing Early sowings in a cold frame or under cloches 1cm (½”) deep. Later sowings outside in rows 1cm (1 ½”) deep with 10cm (4”) between the rows. Planting Salad or Spring Onions do not need transplanting or thinning. Remove cloches or frame cover by mid April. Pull alternate Onions to naturally thin the crop during the season. Growing Tips Always worth sowing Salad Onions in small batches for an all Summer harvest, near Carrots, as this can help prevent carrot fly attack.