NEWTON PARK HORTICULTURAL SOCIETY
Onion Sets (Autumn planted)
Soil Fertile, well drained soil with compost dug in. In clay soil, grow in raised beds or rows.
Position Sun or partial shade.
Frost tolerant Yes.
Feeding Not normally required, though overwintered sets can be given a liquid feed in spring.
Companion plants Beetroot, Lettuce, Cabbage, Strawberry.
Spacing Single Plants: 15cm (5") each way (minimum)
Rows: 15cm (5") with 25cm (9") row gap (minimum)
Sow onion sets directly into the soil from autumn onwards.
Japanese variety onion sets can be used to give an early harvest. Onion sets are also the better choice for heavier or wetter soils.
Harvesting Harvest as soon as they reach a reasonable size. If storing them, wait until the tops start to die down and dry for about 10 days.
Troubleshooting Weed early and often to keep onions growing strong. Seedlings are less likely to bolt (produce flowers) compared to bulb onions grown from sets.