When to plant Onions in Perth

Allium cepa

Onion
Onion · Allium cepa

A hardy allium for UK gardens, grown from sets. Plant spring sets for a summer crop, or named overwintering sets in autumn for an earlier lift. It needs free-draining soil, steady weeding, and a careful cure before storing.

45 cm · Full Sun · Moderate Water

Add to garden

Calibrated to Perth · last frost ≈ 9 May

Plant out August to September, harvest May to August. Frost risk October to May.
ActivityJanuaryFebruaryMarchAprilMayJuneJulyAugustSeptemberOctoberNovemberDecember
Plant outNoNoNoNoNoNoNoYesYesNoNoNo
HarvestNoNoNoNoYesYesYesYesNoNoNoNo

Growing guide

What to do through the growing season

Growing guide for

Change the guide to see different planting timelines and tips.

Plant named overwintering sets in free-draining soil for an earlier crop. Do not use spring sets.

  1. 01

    Prepare the Bed

    31 Jul to 14 Aug

    Prepare the bed around 31st July - 14th August. It must drain freely. Work in garden compost or well-rotted organic matter. Do not add fresh manure.

  2. 02

    Plant Overwintering Sets

    14 Aug to 25 Sept

    Plant named overwintering sets around 14th August - 25th September, tips just showing. Do not plant spring sets. Space apart, in rows apart. Firm the soil. Water if it is dry.

    • In a mild town, wait until the soil is cooling. Too much autumn leaf can raise the risk of bolting in spring.
    • Birds lift sets. Cover with fleece or mesh until they root.

  3. 03

    Keep Weed Free

    14 Aug to 13 May 2027 Dates as each sowing reaches this stage

    From 14th August to 13th May 2027, keep weeds down. Hand-weed close to the bulbs. Water in dry spells once growth restarts, then ease off when the leaves begin to yellow.

  4. 04

    Lift and Cure Bulbs

    21 May to 21 Aug 2027 Dates as each sowing reaches this stage

    Lift bulbs through 21st May - 21st August 2027, when the tops yellow and fall over. Dry them somewhere warm and airy for two to three weeks, then trim the roots and loose tops before storing.

Suggested varieties

Popular varieties of Onion to consider

Sturon

A dependable maincrop onion with good storage qualities and firm, globe-shaped bulbs.

Red Baron

A reliable red onion with good colour and a steady crop from sets or transplants.

Senshyu Yellow

A well-known overwintering onion that can be planted in autumn for an early summer harvest in mild UK gardens.

Centurion

A widely grown, high-yielding set onion with good tolerance to bolting.

Onion guides by town

See how Onion timing shifts in other towns with different frost dates.