How To Grow Onions From Sets

Snowball onion set

Snowball onion set

Onions are one of the nicest things to grow in your garden and one of the first crops to plant in spring. I always feel that once I plant my onions, then my gardening year has really started. They are relatively easy to grow and once you follow a few guidelines, should provide you with one of the best crops of the year. They can be stored for months in the correct conditions and are a staple of most culinary dishes.

You can of course, grow onions from seed but I would advise against it unless you have the time, patience and a greenhouse/polytunnel. Instead, I would recommend you get yourself some onion sets. Onion sets are partly grown onion bulbs, they are usually more reliable than growing from seed and because you are growing from set, there will be less work as there is no thinning required.

Recommended Varieties:
White Onions: Stuttgarter Giant, Sturon
Red Onions: Red Baron, Karmen

Planting:

When planting your onions, prepare your soil a few weeks in advance by adding some compost or soil enricher. Onion sets will need to be spaced properly to give them space to mature and bulk up. Space your rows about 30cm apart and plant your sets about 10-15cm apart. Plant each set with the neck facing upwards, leaving the tip above the surface. Firm these in well and water.

Onion sets being planted

Onion sets being planted

Growing:

Young onion plants are very, very appealing to birds and because you leave them poking their heads out, you’ll need to protect them with some netting so the birds won’t rip them out from the bed. Frost can be another issue for young onions so wait until mid-late March to plant them. Frost can push your sets out of the soil so be vigilant and push them back in. I often keep an eye on the weather report and put fleece over my onion crop if a ground frost is on it’s way.

You will need to weed in between your young onions a lot as they hate weed competition. Take care not to disturb your sets from the soil while weeding. I have a great hand held onion hoe for this purpose, an old dinner fork also works well.

That's my onion hoe in the centre, brilliant for weeding between my onions

That’s my onion hoe in the centre, brilliant for weeding between my onions

Harvesting:

Onions are usually ready to harvest in mid summer. Their tops will start to fall over and yellow. Loosen the soil around them and lift them gently with a fork. Onions will need to dry out, it helps if you harvest them on a sunny day. Hang them in an airy, dry place (like your shed) for about three to four weeks to dry them for storage.

Dried onions

Drying onions

Bolted Onions:

The biggest problem I seem to have experienced when growing onions is bolting. Bolting is essentially when a plant begins to flower, which of course is pretty (especially allium flowers), but not very useful when producing food as you want the energy to go into the food and not into producing seed. It generally occurs when the spring and summer are particularly wet and chilly.  Bolted onions won’t store well at all and I have found red onions particularly prone to bolting early. If they do bolt on you, snap off the thick flower stalk just above the bulb. Bolted onions will not mature any further and could likely rot in the ground in wet conditions so your best bet is to harvest it and use it within a week as it won’t store well.

Bolted onion form last summer, very pretty flowers

Bolted onion from last summer, very pretty flowers

I just bought my onion sets today an will be planting them this weekend. This year I’m growing Sturon for my white onions and Karmen for my red onions as I have had success with both varieties before. I’m also going to plant some spring onions and garlic and have my leeks germinated and growing strong at home. Looks like I have my allium beds sorted for 2014.

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4 thoughts on “How To Grow Onions From Sets

  1. cissyblue says:

    Reblogged this on cissyblue and commented:
    Please forgive us here at the farm in central Te’jas, for re-blogging some gardening posts… we believe they are good info to have, even though it is off-topic just a bit… plants are one of my devotions…

  2. Orlaith says:

    I find only sets bolt; especially Autumn sown ones, whereas seed onions pretty much never bolt. That said, I’m risking sets this year due to a time shortage, and 100 went in today. As regards the birds issue, I never cover mine with nets, and so far have never had any moved. Rather than leave the tips exposed, push the set just under the surface. That way they’re not visible, but will still sprout just fine. It’s the same with garlic. Fingers crossed for a good year, coz there are few worse smells than that of a bolted, rotting onion.

    • FionaGrowsFood says:

      I’ve not attempted to grow from seed yet, I think I might try it next year though. I had a load of bolted onions last year, the smell was horrendous, almost as bad as potato blight, almost!

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