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growing tall cosmos - rich soil?

FireFire Posts: 19,096
in Problem solving
Hi, I have a lot of seedlings of tall cosmos varieties. I have three beds I was planning to put them in, but they are new (created in the last year) made up of much compost and manure - added to help, long term, with the heavy clay. This is going to make the earth much too rich to give the mass of summer blooming flowers I was planning. Last year I planted one cosmos and it reached six foot tall and started flowering in October, finishing with the frosts. It was, essentially a tree. I have grit to add to the beds, but I don't think this will help with the richness problem. Short of planting everything in pots, do you have any suggestions to make for July/August flowering plants without a mass of jungly foliage?

Thanks
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Posts

  • hogweedhogweed Posts: 4,053
    When did you plant your 1 cosmos last year? was it late?
    If you pinch out the tops when you plant them they will be sturdier.
    'Optimism is the faith that leads to achievement' - Helen Keller
  • FireFire Posts: 19,096
    edited May 2018
    I did plant it late, and no, I didn't pinch out the tops. Do you think it would flower in the summer if I planted into manure mix?
  • Kitty 2Kitty 2 Posts: 5,150
    I've had the 'monster cosmos' at over 7ft tall, despite the advice to pinch, pinch, pinch from others on the forum.
    The only time they've stayed short was last year when I kept them in pots filled with old spent compost.
    Could you keep them potted, but stand the pots in the border where you want them?

    Always flower late summer/early autumn up here though. Usually sow seed in March, not bothered this year 😕.
  • Blue OnionBlue Onion Posts: 2,995
    Make a new skinny bed by removing a strip of grass next to a patio or path and planting them along there?  Plant them a bit closer than before for competition, which I suppose may keep them smaller and bring on flowers earlier?  
    Utah, USA.
  • FireFire Posts: 19,096
    Ah, I don't have any grass, Blue, but thanks for the thought. I will see what I can come up with.
  • Blue OnionBlue Onion Posts: 2,995
    edited May 2018
    Haha.. too many plants, ay?   :D. Maybe you have somewhere else that hasn't been improved?  Or next to another hungry feeder?  

    I planted mine out a few days ago.  I was planning to put them next to the hollyhocks along the neighbors horrid white vinyl fence.. but discover the soil was bone dry, despite just having run the sprinklers the night before.  (That would explain why only bindweed grows in that part of the lawn -and not grass!).  So I ended up sticking them under/around a youngish plum tree.  We'll see how that works out.  
    Utah, USA.
  • FireFire Posts: 19,096
    The previous owners took out the grass and I'm thankful they did. I have borders and woodchip path instead. V low maintenance. I think that either a) I'm being neurotic and the cosmos will be fine or b) my garden really isn't suited to growing plants that like loads of sun and poor soil. Tbh, I started the seeds before I fully realised that cosmos like conditions such as Mediterranean plants, lavender, rosemary, oregano etc. The bits of garden that aren't covered in manure are solid, hard clay, so I don't think that will be great either.
  • Blue OnionBlue Onion Posts: 2,995
    I've grown them in several states and in the U.K. (Surrey) without one bit of trouble.  Everything from the damp clay of Pennsylvania, the sandy soil of Virginia, and now the desert of Utah.. they've always just grown, bloomed, and did their thing.  I suggest you just pop them in wherever there is space, and see which plants are happiest.  Then next year, you'll know where to put them.  I've never found them fussy (or six feet tall!).. but perhaps I was just lucky.  I've mainly stuck to the standard variety, but have occasionally grown the seashell mix when I've had a packet to hand.  
    Utah, USA.
  • FireFire Posts: 19,096
    Yes, I shall use this year as an experiment (as most of the rest of my seedlings are this time). I shall plant the cosmos in every spare spot and see what happens. I'm sure if they can cope in a desert, they can deal with north London. I think I've got enough back ups, if nothing happens with the cosmos. I do love them, so would be disappointed if they come to nothing, or don't flower before the frosts. But worse things happen at sea!
  • fidgetbonesfidgetbones Posts: 17,618
    I've grown them in clay, and in shade. Just stick them in and see what happens.
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