To Set or To Seed?

Is it better to grow onion from seeds or from sets?

Hello friends!
I’m just going to start off by saying that this is not a ‘how-to’ with regards to growing onions. If you’re looking for advice on growing onions, then have a look over here where you’ll find everything you need. This post that you are reading is about the pros and cons to growing onion from seeds and sets so I’ll assume that anyone reading it already knows the onion growing basics.

So I’m experiencing this classic dilemma that many vegetable growers have probably experienced. In the three years that I’ve been growing onions, I’ve always used onion sets.
Now I’ve always been curious about growing onions from seed but never quite had the confidence to do it. It seemed a bit of a gamble to mess around with seeds when sets are pretty much guaranteed to work. However this year I aim to grow a lot more onions, and it seems that I can save myself a bit of money by growing them from seed rather than buying the sets. Of course money isn’t the only thing you should take into account when planning a vegetable patch so I’ve been doing some research to try and figure out whether the switch to seed is going to be worth it.

This is the main reason tha I’m considering growing onion from seed. Obviously onion sets have been through a longer process so when paying for them you’re paying for extra labour, storage, packaging etc. When paying for seeds, you’re pretty much just paying for seeds. So for example, looking at Red Baron onions. For a bag of 50 sets you’d pay £3.95 and assuming all of those onions survive and grow successfully, you’d be paying 8p per onion. However if you were to buy Red Baron seeds, you pay £2.29 for a packet of 150 seeds (prices from Mr Fothergills 2018).  Assuming that those seeds all make it to onion-hood then you’ve paid approx. 1.5p per onion. When you’re talking about a matter of pence, it doesn’t sound like a massive difference but it’s very, very true that if you look after the pennies, the pounds take care of themselves. For Rick and I who are on a mission to become self sufficient, every little helps.

I have had onions bolt every year and it’s infuriating. I water them regularly and use heat treated sets but this doesn’t make a difference, I will always get a few of my onions bolting. I just accepted it as part of life. According to onion sets are more likely to bolt as they are already in their second year of growth when they’d naturally want to flower and produce seed. Planting onion seed in late winter to be harvested in the summer means that they are far less likely to bolt. It doesn’t rule the possibility of bolting out but it makes it less likely. So this is a huge plus for me.

Onion sets are basically already half developed so will take less time to mature to harvesting stage. Seed obviously has a much longer way to go when you buy it, potentially taking up valuable space in your greenhouse. For me this isn’t much of an issue. Here in Northumberland I’m not even going to think about sowing tomatoes in my greenhouse until late March/April time. Onion seeds really should be started off around January indoors in order to harvest them that same year. With seed having a longer growing season this does often mean that they get a chance to grow into a larger bulb.

Onion sets are basically already half grown as previously stated and so are naturally going to be less susceptible to disease, they’ve basically already through the most vulnerable stage. I’m not saying that sets are immune to disease, just that there’s less chance of them dying on you. Seeds obviously have to go through germination, seedling, being transplanted etc and there are many things that can go wrong in those stages.

When you go to the garden centres to buy onion sets, there are usually only a few varieties in each type of onion. And sometimes you’ll literally just see ‘Red Onions’ or ‘Brown Onions’. When you go to buy onion seeds, you’re going to have a far wider range to choose from. For me this is a huge selling point. I want to experiment with different onion seeds to see which oonions will store best, which ones will turn out pretty for showing, which ones will do best in the soil here etc.

So here’s a little list of summary points just in case you didn’t want to read all of that waffle!

Onion Sets
Are generally easier to grow.
Will reach maturity and harvest point a lot more quickly.
Less prone to disease

Onion Seeds
More varieties of onions available to choose from.
Onions are less likely to bolt as they are in their first season of growth.
Saves you money if all the onions you grow are successful.

So this is what I’ve found out on my research mission. I hope this helps some of you in your onion growing journeys.
Does anyone have any insight into growing onion from seeds or sets? Have you had more success or failure with one or the other? Leave any comments in the comments section below.

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  1. Very interesting Ellie. I might have a go at growing from seed once my grounds (&neighbouring gardens) are disease free. I have to wait a few years yet though

    1. Thanks! Which diseases are present? Just out of interest.


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