Growing Onions From Sets
Owen Petrakis · Oct 21, 2026 · 5 min read
Quick answer
Onion sets are an easy, reliable way to grow onions with little effort.
Onion sets are small, immature onions that grow into full-size bulbs. They are easier than growing from seed.
Autumn and spring varieties are available.
1 When to plant
Plant autumn varieties in autumn for early summer harvests, and spring varieties in early spring for late summer harvests.
2 Planting
- ✓Choose a sunny, well-drained spot
- ✓Push sets into soil so the tips just show
- ✓Space about 10 cm apart in rows 30 cm apart
- ✓Net against birds, which pull sets out
3 Care
Keep weed-free, as onions do not compete well. Water in dry spells but stop once bulbs swell to improve storage.
4 Harvest and storage
Harvest when leaves yellow and flop over. Dry bulbs in a sunny, airy place for a couple of weeks, then store somewhere cool and dry.
5 Bolting
Onions sometimes bolt — produce flower stalks — especially after cold spells or dry weather. Bolted onions are still edible but will not store well. Snap off flower stems and use these onions first. Heat-treated sets reduce the risk of bolting. Avoid planting spring sets too early in cold, wet soil.
This is general gardening information. Results depend on your climate, soil, and conditions. Follow label directions for any fertiliser or treatment, and check whether plants are toxic to pets or children before bringing them home.