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Onion Sets Never Swell

Dawn13Dawn13 Posts: 37
in Fruit & veg
So I'm having an ongoing problem that my onion sets never swell to maturity.
They seem to root well and grow good, strong foliage. But once that dies away nothing happens.
Interestingly, the first time I grew onion sets - and didn't know what I was doing - I planted them fully underground and they grew beautifully.
Now I'm following the rules I'm having zero success!
Perhaps I'm leaving too much above ground.
Any ideas from the more experienced growers here???
Thank you!!!
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Posts

  • ObelixxObelixx Posts: 30,090
    I've always buried mine to their own depth.  It helps them get more moisture and also reduces the ability of birds to peck them out of the ground.   They will then grow good roots to anchor and feed them and the bulbs will eventually well up above ground.
    Vendée - 20kms from Atlantic coast.
    "The price good men (and women) pay for indifference to public affairs is to be ruled by evil men (and women)."
    Plato
  • Dawn13Dawn13 Posts: 37
    Obelixx said:
    I've always buried mine to their own depth.  It helps them get more moisture and also reduces the ability of birds to peck them out of the ground.   They will then grow good roots to anchor and feed them and the bulbs will eventually well up above ground.

    Thank you so much for your reply. This is really interesting and I appreciate you sharing your experiences! Definitely going to try this next year. Thanks again!
  • BobTheGardenerBobTheGardener Posts: 11,385
    I always start onion sets off in modules in the greenhouse, then plant them out once the leaves reach about 15cm high.  I'm a little confused about you saying:
    "They seem to root well and grow good, strong foliage. But once that dies away nothing happens."
    That is normal - onions only increase in size while they have leaves, once those have died-back (normally about July/August for spring-planted sets), they won't get any bigger if left in the ground, so that's the point you harvest them.


    A trowel in the hand is worth a thousand lost under a bush.
  • Dawn13Dawn13 Posts: 37
    BobTheGardener said:
    I always start onion sets off in modules in the greenhouse, then plant them out once the leaves reach about 15cm high.  I'm a little confused about you saying:
    "They seem to root well and grow good, strong foliage. But once that dies away nothing happens."
    That is normal - onions only increase in size while they have leaves, once those have died-back (normally about July/August for spring-planted sets), they won't get any bigger if left in the ground, so that's the point you harvest them.



    Thank you so much for your reply.

    This is very interesting... so I thought the majority of the swelling happened after the foliage had died back? Culminating in harvest in autumn. I've probably got confused and need to do a bit more research. Thank you.

    Either way, the onions have only swelled to a very tiny 1.5 inches in diametre rather than the 3-5 I was expecting sadly.

    Thank you again!!!
  • BobTheGardenerBobTheGardener Posts: 11,385
    edited October 2021
    Onions are quite heavy feeders, so it's worth adding some general fertilizer to the soil in the rows before planting, if you aren't already doing that?  I use blood, fish and bone which is sprinkled along the row and then hand-forked in before planting the sets.  They also don't compete well with weeds, so it's important to keep weeding.
    PS: quite a few have had poor onion harvests this year, probably due to the strange weather patterns early on, so you might not be doing much wrong. :)
    A trowel in the hand is worth a thousand lost under a bush.
  • Dawn13Dawn13 Posts: 37
    edited October 2021
    BobTheGardener said:
    Onions are quite heavy feeders, so it's worth adding some general fertilizer to the soil in the rows before planting, if you aren't already doing that?  I use blood, fish and bone which is sprinkled along the row and then hand-forked in before planting the sets.  They also don't compete well with weeds, so it's important to keep weeding.
    PS: quite a few have had poor onion harvests this year, probably due to the strange weather patterns early on, so you might not be doing much wrong. :)

    Again, this is really interesting! I'd read somewhere onions didn't like a fertile environment so planted them in old compost and avoided feeding!!!!

    This is what I love about gardening... always so much to learn and a great deal of that has to be done personally through trial and error.

    So, I have lots of new ideas for giving onion sets another go next year. I won't give up.

    Thank you so much for your help.

    I only have a patio where I grow all my home grown food and the majority of my flowers. I have a lawn too but my landlord has forbidden me to dig it in any way. However, he said nothing about small wildflower patches and hasn't noticed yet! Am hoping to get an allotment soon!
  • BobTheGardenerBobTheGardener Posts: 11,385
    Perhaps you got mixed-up with carrots?  Those grow well in pre-used compost and don't need much in the way of feeding.  I did a bit of googling and can see some say onions don't need much feed and some say they are gross feeders - the internet is like that!  The RHS say:
    If in doubt, it's always worth checking their advice. :)
    A trowel in the hand is worth a thousand lost under a bush.
  • Dawn13Dawn13 Posts: 37
    BobTheGardener said:
    Perhaps you got mixed-up with carrots?  Those grow well in pre-used compost and don't need much in the way of feeding.  I did a bit of googling and can see some say onions don't need much feed and some say they are gross feeders - the internet is like that!  The RHS say:
    If in doubt, it's always worth checking their advice. :)

    Do you know what... you are so right!!! I grow my carrots every year in old compost, with great success. I think I've confuzzled the advice at some point, transposing it to onion sets.

    Some radical changes to growing onion sets next year then! I'm looking forward to it already...

    And I agree about Internet advice... there is so much conflicting guidance. And I do often get led astray!!! I should be more selective, and RHS is great. Thank you for sharing their instruction with onion sets. Much appreciated!





  • ObelixxObelixx Posts: 30,090
    Sometimes the RHS advice is a bit old-fashioned - eg double digging - but they have loads of info on all sorts of crops/plants/growing healthy plants that I always start there.  Garden organic is another good one. 
    Vendée - 20kms from Atlantic coast.
    "The price good men (and women) pay for indifference to public affairs is to be ruled by evil men (and women)."
    Plato
  • nick615nick615 Posts: 1,487
    From my experience, please don't get depressed about conflicting advice.  Ask four different gardeners, and you'll probably get at least three lots - because everyone tells you to do what they do, i.e. that which suits their plot.  Onions and leeks each like chicken manure pellets, coupled with plenty of moisture so I scatter pellets on the area I set aside for the season's crop, plus a good inch of lawn mowings and a sheet of roofing felt with holes.  These last two items help keep weeds at bay.  My sets are planted to about half their depth and left to get on with it.  Hopefully two pics attached.
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