Onions in Glaschoil

Allium cepa

Onion
Onion · Allium cepa

A hardy allium for UK gardens, usually grown from sets for the easiest crop or from seed for more choice. It needs free-draining soil, steady weeding and a careful cure before storing.

45 cm · Full Sun · Moderate Water

Add to garden

Calibrated to Glaschoil · last frost ≈ 10 Jun

Plant out May to June, harvest October. Frost risk August to June.
ActivityJanuaryFebruaryMarchAprilMayJuneJulyAugustSeptemberOctoberNovemberDecember
Plant outNoNoNoNoYesYesNoNoNoNoNoNo
HarvestNoNoNoNoNoNoNoNoNoYesNoNo

Growing guide

Step-by-step instructions for growing Onion

  1. 01

    Prepare the Bed

    26 Apr to 11 May

    Work the soil from 26th April - 11th May, making sure it drains freely and has a fine tilth. Mix in compost or well-rotted manure, but avoid fresh manure, which encourages soft growth and poorer bulbs.

  2. 02

    Plant Sets

    27 May to 10 Jun

    Plant sets from 27th May - 10th June, with the tips just showing above the soil. Space them apart in rows apart, then water in thoroughly straight away.

  3. 03

    Keep Weed Free

    3 Jun to 1 Oct every 3 weeks

    From 3rd June to 1st October, hoe between rows lightly and hand weed close to the bulbs so they do not get crowded out. Water during dry spells while the bulbs are swelling, and keep the soil evenly moist rather than soggy.

  4. 04

    Lift and Cure Bulbs

    1 Oct to 31 Oct

    Lift bulbs from 1st October - 31st October when the tops yellow and fall over. Dry them in a warm, airy place for before storing, then trim off roots and loose tops once they are fully cured.

Companion plants

Tap a plant to see why it works (or doesn't) with Onion.

Good companions

Plants to avoid

Why companion planting matters

Companion planting can deter pests, improve pollination, and make better use of space. Some plants confuse pests or attract beneficial insects; others improve soil or offer shade to neighbours that need it.

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.