Onions in Pen-Iôn

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 Pen-Iôn · last frost ≈ 22 Apr

Plant out April, harvest August to September. Frost risk November to April.
ActivityJanuaryFebruaryMarchAprilMayJuneJulyAugustSeptemberOctoberNovemberDecember
Plant outNoNoNoYesNoNoNoNoNoNoNoNo
HarvestNoNoNoNoNoNoNoYesYesNoNoNo

Growing guide

Step-by-step instructions for growing Onion

  1. 01

    Prepare the Bed

    8 Mar to 23 Mar

    Work the soil from 8th March - 23rd March, 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

    8 Apr to 22 Apr

    Plant sets from 8th April - 22nd April, 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

    15 Apr to 13 Aug every 3 weeks

    From 15th April to 13th August, 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

    13 Aug to 12 Sept

    Lift bulbs from 13th August - 12th September 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.