Overwintering Onions Trial

This year we will be experimenting with overwintering onions, and comparing them to onions we plant in spring next year.

Will they survive the winter? Will they provide an earlier harvest than spring planted varieties (they should do!), and if they do, how much earlier? That’s what we want to find out.

Overwintering Onions Trial - onion sets

Overwintering Onions Trial – Varieties

We are including the following onion varieties in our trial:

  • Onion Set Troy
  • Onion Set Electric (red onion)
  • Shallot Yellow Moon

These are actually part of a set provided by Suttons Seeds. It is always exciting to receive a parcel! However, a look out of the window at the cold, rainy, October weather soon tempered the excitement. Nevertheless, planting onions in October is one less job for the spring, one of the busiest times of the gardening year.

Overwintering Onions Trial - Suttons Box

Onion Planting Method

The onion bed was prepared as follows:
(you may also like to see our guide to overwintering onions)

  • Dug over with a spade and weeded
  • Rows marked out with canes and twine, spaced 30cm or 12″ apart
  • Rows dug over with a fork, and then raked
  • Row was walked over once to compact the soil a little before planting (our soil is light and sandy)
  • Bulbs pushed into soil, spaced around 15cm or 6″ apart (a little further for shallots). Tips of the bulbs just showing at soil level.

Date of planting was Tuesday, 15th October on a dry and moderately warm day in the South East of England.

Overwintering Onions Trial - Netted Beds

The final result of the hard work is shown above. At time of planting, it is a good idea to cover an onion bed with a net. Birds do not actually eat the sets, but they have an annoying habit of picking them up to discover if they are edible. From experience, it can be frustrating to return to an allotment to discover onion bulbs thrown all over the plot!

The Results

The plan is to provide regular updates on our site throughout their growth.

If you would like to conduct your own experiment please see the links below and feel free to comment on our post or facebook page. It would be great to hear your experiences too!

A Selection Of Overwintering Onions

Sutton Seeds 720

The following onion varieties are suitable for overwintering. These have been selected from Suttons Seeds, or see their whole onion range here.

Overwintering Onions - Early Crop Radar

Early Crop Radar

Harvest from mid-May. Mild taste. Pale mid-brown skin.
Read more on Suttons Seeds.
Overwintering Onions - Electric


Harvest May/June. Good flavour. Pink flesh.
Read more on Suttons Seeds.
Overwintering Onions - Senshyu Yellow

Senshyu Yellow

Harvest in July. Japanese variety. Heavy crops. Straw coloured.
Read more on Suttons Seeds.
Overwintering Onions - Troy


Harvest June/July. Heavy crops of yellow skinned onions.
Read more on Suttons Seeds.

See all onion varieties sold by Suttons Seeds.