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Underplanting cosmos?

maryyarwoodmaryyarwood Posts: 5
in Plants
I have grown cosmos from seed and they are out in the garden. What late annuals could I plant to cover the soil around them or do they need to be on their own? I get confused when it says plant spacing distance - does that mean nothing else should be growing in the same space? 

Posts

  • Pete.8Pete.8 Posts: 11,340
    I think if they were mine, I'd pinch out the tops on them which will make them much bushier and will fill the space between them. I'd snip off the top 4" from each of the plants then all the side shoots will grow out and fill the space.
    If you leave them they'll just get much taller and inevitably snap if/when we get some stormy weather and most of the flowers will just be at the top of the plants.

    Billericay - Essex

    Knowledge is knowing that a tomato is a fruit.
    Wisdom is not putting it in a fruit salad.
  • KiliKili Posts: 1,104
    edited July 2020
    Do as pete 8 says but there's no need for underplanting. When they get going there going to swamp that small space and anything underplanted will simply be overpowered by the cosmos. I always call them the thug plant lol.. great for filling a border but hard to have anything else with it for the reasons I've described.

    Maybe some trailing lobelia or petunia right at the front to spill out over the wall but anything with any height forget it.

    'The power of accurate observation .... is commonly called cynicism by those that have not got it.

    George Bernard Shaw'

  • maryyarwoodmaryyarwood Posts: 5
    Thanks Pete and Kili - love this forum already! I did wonder about pinching them out but couldn't find any advice on whether this was a good idea. Will do this as it makes sense and they did get big but floppy last year. I wondered about lobelia too - might give it a try, guessed there would be no room for anything with height. Thanks again, sometimes I just need a nudge to try things out! 
  • Pete.8Pete.8 Posts: 11,340
    Cosmos are really tough pants and they can get huge - much taller than stated on the packet.
    When my seedlings have about 5-6 pairs of leaves and are about 6" tall I pinch out the tops to get bushy plants. 
    I had cosmos Purity a couple of year ago and one plant covered an area about 6ft x 6ft. The main stem and several side branches snapped in strong winds but it just carried on growing and flowering

    Billericay - Essex

    Knowledge is knowing that a tomato is a fruit.
    Wisdom is not putting it in a fruit salad.
  • maryyarwoodmaryyarwood Posts: 5
    Wow! These just say 'Cosmos bipinnatus' , height 100cm, to be spaced at 30cm. It's lumping down right now but I'll pinch them out tomorrow. 
  • Blue OnionBlue Onion Posts: 2,995
    I have my cosmos in a mixed pollinator garden.. they do just fine planted right next to other annuals.  As others mentioned, they do bush out if there is the space.  I suggest you squeeze some lower growing annuals right along the front next to your stone edge.  Buy up six small bedding plants.. maybe something white to go with the colors of the cosmos?  Maybe some Alyssum?

    Utah, USA.
  • LoxleyLoxley Posts: 5,698
    You could always plant a cheap, sacrificial tray of trailing lobelia. It will get swamped by the cosmos but will fill the gap temporarily.
    "What is hateful to you, do not do to your neighbour". 
  • maryyarwoodmaryyarwood Posts: 5
    Thanks for your suggestions 

  • FlyDragonFlyDragon Posts: 834
    edited July 2020
    My cosmos are growing up through a carpet of nasturtiums and are also surrounded by other wildflowers.  Not deliberately, but as a result of two years attempts at a wildflower patch suddenly coming to life all at once.  It actually looks nice if a bit chaotic!  And there are loads of bees and butterflies already even though the Cosmos haven't flowered yet. 
  • strelitzia32strelitzia32 Posts: 758
    @Loxley I'm convinced lobelia should be called invasive! I'm constantly pulling it out, it's worse than forget me nots. I had some trailing out a single basket a few years ago, it seeded everywhere.
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