Onion Growing Guide

Allium cepa


Crop Rotation Group

Allium (Onion family) 


Fertile, well drained soil with compost dug in. In clay soil, grow in raised beds or rows.


Sun or partial shade.

Frost tolerant



Not normally required, though overwintered sets can be given a liquid feed in spring.


Single Plants: 15cm (5") each way (minimum)
Rows: 10cm (3") with 20cm (7") row gap (minimum)

Sow and Plant

Easiest to sow onion sets (tiny bulbs) which are planted direct into the soil from autumn onwards. Can also be grown from seed in which case start in pots under cover in late winter before planting out mid-late spring.
Our Garden Planner can produce a personalized calendar of when to sow, plant and harvest for your area.


Japanese variety onion sets can be used to give an early harvest. Onion sets are also the better choice for heavier or wetter soils.


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.


Weed early and often to keep onions growing strong. Seedlings are less likely to bolt (produce flowers) compared to bulb onions grown from sets.

Planting and Harvesting Calendar

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