Overwintering onion sets

So today I have been and planted my onion sets to overwinter. I didn’t plant any sets last year and I feel like I missed out somewhat! I had lots and lots of seeds so thought that I would just sow those and they would give me enough onions to get me through the summer. That theory didn’t really pay off as they didn’t grow as big as sets do and I didn’t have enough space by the time summer really set in as I had so many other crops I wanted to plant. My plan for this year is to do both as we have a bit more room so I will also sow some seeds in the greenhouse in the spring to see if I can get a big enough harvest to not have to buy onions.

Onions are really slow growers and need a lot of time so the real benefit to planting onion sets is that you can overwinter them. So any planted in the autumn are in the ground over the winter and by May or June the following year they are ready to come out to be dried and then stored. This then frees up your patch for the more tender vegetables that don’t like the frost such as courgettes, squash and runner beans. I really am determined to make full use of all available space and not have any of my plot empty so this makes the most sense to me.

I usually plant onion sets in the beds that I have previously grown potatoes. This is not only good practice as far as crop rotation is concerned but as main crop potatoes often aren’t ready until late summer it is perfect timing to use the space once they have been dug up. The soil is usually in great condition as we mulch our potatoes and earth them up with a mix of compost, leaf mould and grass clippings from the lawn. By the time we are ready to dig the potatoes up everything has rotted down beautifully and the soil just needs a good rake and it is good to go. Onion sets need to be planted about 5-10cm apart and about 2.5cm deep so the tip is poking out of the soil. One year Mr Dig planted the sets without me first giving him instructions. I didn’t think he had done them as I couldn’t see anything. It then dawned on me that he had completely buried them…..luckily they grew really well and gave us a good crop so he wasn’t in trouble!

I have picked two varieties to grow this year. Firstly ‘Electric’ which is a red onion. I love to have red onions as well as white. I grew these last in the 2018-19 period. They grew to a gigantic size and were really tasty. They are due to be harvested late June to early July which means I can use the space for something else. The other variety I have planted is ‘Radar’ which is a Japanese Heritage ultra hardy onion. I picked these as if you plant early enough they can be ready to harvest in May. Again this gets them out early enough that I can get something else in the space they have been occupying for a good summer crop. This variety is also good for storing and will store for up to a year. I have usually eaten them all within 6 months but if I had more space and could plant enough to sustain us for a year I would!