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Onion sets

Over the last few years, I have grown onions from seed ( I have some in root trainers now) however, I did purchase 50 onion sets, my onions in the past have been a bit up and down. So any advice from the forum might help. In the past my onions have never really grown very big, I had some big show-winning ones in and some Bedfordshire champ, I harvested some near the end of the season, but I left a lot of them to grow on a little, they didn't! and so I need help, Question 1. watering and feeding? when and how often, feed which is best. Question 2. when to harvest? and Question 3. do you expose the upper part of the onion even in the bright sunshine. sorry about all the questions.


  • fidgetbonesfidgetbones Posts: 17,442
    They don't tolerate weeds around them very well, so yes, you do need to keep the bulbs exposed. The onions put on leaf until about midsummer day, then they start ripening. They need good conditions, food, water and sunshine before then. The biggest onions come from specialist seed. Kelsae and Robinsons Mammoth are the two that grow to football size. Seed for giants is traditionally sown on xmas day, and they are mollycoddled  until they get planted out.  I sowed mine end of January  , also in roottrainers. They will get big enough for me. I have kelsae this year. I never do very well with sets.  For food I use home made compost or well rotted farm yard manure, liberally dug into the soil. Then just before I plant I use blood fish and bone.   The growing for show lot have their own special recipes.
  • Nanny BeachNanny Beach Posts: 8,669
    Only manure the ground the previous autumn
     Have never grown from seed
     Only grow the same variety because they do so well.sturon, Stuttgarta,red electric. Have found they "keep" I have still got 2 red,from last September
     All the others have been eaten. They are rarely watered never fed. North facing veg plot,but big garden open aspect gets sun from morning till lunch time then again till sunset
  • ColinAColinA Posts: 386
    I always start my onion sets in plug trays in the green house in early to mid March harden off then plant out when leaves have grown to about 4-5 inches tall. Like Nanny Beach I grow Sturon or Rumba every year and I was told to  regularly water in hot or dry weather to stop bolting and i only feed with Comfrey mix
  • pclark42pclark42 Posts: 185
    Very interesting, my garden is South facing in south Leicestershire, the weed thing that fidgetbones mentioned may be a problem, I was a bit useless for a while with eye trouble, and the weeds got quite bad.
  • bertrand-mabelbertrand-mabel Posts: 2,594
    Grew some from seed one year and hardly made the size of a shallot.
    Last year went back to sets and we had the best large onions for years. We did have to keep putting them back in the ground and had to cover them with a mesh until the new growth was a decent size.
    Was going to plant them out today but heavy winds and rain put stop to that.
    We don't feed them apart from puttting home made compost on the bed before planting in the winter.
    Yes they are watered if we have many weeks of no rain as they are developing.
  • SkandiSkandi Posts: 1,721
    I plant the sets just under the ground so nothing is showing, I find that by the time the green shoots break the surface the roots are strong enough to hold them in against the birds.
    I put compost down but that is all the fertilising they get, they get watered if we go longer than a week without rain.
    I don't unearth the bulbs at all, they seem quite happy to do it themselves.
    I've grown both from seed and from sets, I get the same result, but I find sets are ready a few weeks earlier and I don't have to run lights in the house for a month with sets like I do with seeds.
  • pclark42pclark42 Posts: 185
    You have all made me think quite a lot, last year I grew the onions in a 'no-dig' plot, only made 3 months earlier by placing cardboard down, and covering it with good compost. I wonder if that was the cause of my problems, the compost was quite dry, I soaked it for ages the month before planting, after 6 or more months the weeds still appeared, but I think they were windbourn.
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