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


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


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


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.


Lá Fhéile Pádraig

Happy St Patricks day from a cold, wet and snowy Dublin. Today is our national holiday and I suppose we are lucky that it is celebrated all over the world but there’s nowhere I’d rather be than here in Dublin, the weather might be terrible but that won’t dampen our spirits (especially if those spirits are whiskeys, vodkas or rums). I tend to avoid the city centre on Paddys day, the parade is great for the kids but I’m not a huge fan of the crowds of drunken idiots. I had planned to spend the day on my plot but the weather is far from being gardening friendly, it’s cold and wet with heavy snow and sleet showers.

St Patricks Day is traditionally the day to plant your first earlies but I’m not growing spuds this year. I did visit the plot yesterday morning in the glorious sunshine (I’m beginning to see why we call it “March many weathers”).


Whiter than white “Snowball” onion set

It was bright and warm yesterday morning, the sky was blue and I spent a few hours on the plot, getting my soil ready for my onions. I planted two types of onion and some shallots. I planted some Red Barons, which I had great success with last year, I also planted some shallots, a variety called red sun which have lovely pink flesh and are slow to bolt. I planted a variety of white onions called Snowball which are lovely pure white onions with a mild flavour. I also have some 50 Stuttgarter sets to plant later this week. I realised after planting my onions that I had no netting to protect them from the pesky birds, who love plucking onion sets out of the soil, so I covered them with some fleece which I had. I’m glad I did now, while onions don’t mind the cold, the frosts can force onion sets out of the ground.


Onions ready for planting


All wrapped up

The plot still looks very bare and messy, it’s going to take some serious hard work to get it the way I want it. Good thing I love getting out and digging because there’s plenty of it to do over the coming weeks.

I hope you all have a great Paddys Day and don’t get too drunk, if you were planning on planting your spuds today, maybe hold off for a few days or you’ll freeze your hands off.

Lá Féile Pádraig Shona Daoibh.

The Grand Stretch

Spring has officially landed! The sun has been beaming for the past few days and it is set to stay that way into the middle of next week. Today was a warm 14 degrees and tomorrow is predicted to get up to 17, almost tropical for March. There’s already a grand stretch in the evenings, as we say here in Ireland, and the clocks go forward in the morning, giving us an extra hour of sunshine in the evenings.

Garden Riddle

Myself and Dave took advantage of the weather the past few days, spending quite a few hours on the allotment. Yesterday, we filled up the car, made a packed lunch and readied ourselves for an afternoon of digging. We dug out the onion bed and the bed for peas and beans. The soil on my plot is a clay soil so can get quite clumpy and requires quite a lot of digging to break it up. We took all of the soil out of the two beds, Dave is really good at this and had them dug out in no time. We turned the soil over for the onion bed and spent a good hour or two just raking it and taking out big rocks and stones. I used a sieve, also known as a garden riddle (I’m learning something new every day) to remove any of the big stones left over after all the digging.

Action Shot

Planted asparagus trench

After some well earned tea and sandwiches, I planted my asparagus. We dug a trench about 20cm deep and 40cm wide, I added in some compost and made a ridge down the centre, I spread the roots of my six crowns out on either side of the ridge and covered them with soil. As they grow, I will continue to add soil and the trench should be level by autumn. I covered them with some horticultural fleece for now to protect them from ground frost. Asparagus is a herbaceous, perennial plant and needs to be planted somewhere it won’t be disturbed. It likes well drained soil and full sun. It has a lovely ferny foliage in the summer months. It should not be harvested for the first two years of growth, which is why many people don’t grow it, however, if you have an allotment, you should try it. It will crop for over twenty years and it one of the nicest fresh vegetables available.

Planting the red onion sets

I planted my onions and shallots today. I planted some Red Baron and Stuttgarter Giant sets. Onions are a great crop, easy to manage and give a great yield for a small space. Space onions about 10 cm apart in rows about 20-30cm apart. If you plant onions closer together they will be smaller and if you plant them further apart, they will grow larger, If you want large onions, all you have to do is give them more space. I planted about 40 red and 40 white onions. I also planted 8 shallots. One shallot set will give you a yield of about 6 shallots. Dave swears by them and often uses them in cooking. I still have about a square metre left in the bed so I might plant a few leeks.There was some glorious sunshine when I was planting the onions and the birds were singing away, it was the first time on my allotment that I’ve forgotten about the digging and felt totally relaxed, it was lovely. I covered my onions with netting to protect them from birds as they will happily steal onion sets from the ground. After about three weeks, the onions will have rooted and the netting can be removed.

Stuttgarter Giant, ready for planting, golden in the sunlight

My....em...extremely "neat" netting for my onion bed

Next week, we’ll be starting construction on the raised beds for my brassicas and carrots. I’m hoping that by next year, I’ll have mostly raised beds in the plot. I’m going to use scaffolding planks to build them as they’re untreated and relatively cheap to buy.

The plot is slowly starting to take shape, it’s still a mess at the moment and it will be at least another few weeks before it looks well. Everything is looking very brown, I can’t wait until the summer when I have some greenery.

I read an interesting fact yesterday, last year in Ireland, gardeners in allotments and at home grew over €9 million worth of fruit and vegetables. Nine million! That’s a staggering amount of produce. That’s 9 million euro not being spent on mass produced, chemically treated food from the supermarket. It’s a very promising figure. I am finding myself more and more interested in growing my own food and buying organic produce, a little effort goes a long way and if we each only grow one successful crop this year, we are still making a difference. I’ll leave you for now with a few photos of the plot the past few days.

Dave made a wigwam out of wood for no apparent reason

Potato Bed

My lovely flask