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Pricking out cosmos

LynLyn Posts: 23,190

As its leggy cosmos seedlings time I thought some may like to see how to prick out very leggy seedlings. I let mine grow on in the seed tray until at least 4" tall, these are 6" they don't need nutrients, the poorer the better for them.

Get a module tray or individual pots, fill with compost, then make a groove diagonally across the pot, lay the seedling on, almost up to the first leaves then gently push down in the centre so the root is uppermost, then gently curl the root end around the pot, don't do them too early, they'll only shoot up again and this way they have grown much sturdier and stronger stems. Pick out the middles and pot on again by the same method when the roots have filled the pots, keep picking out tops and ends of side shoots and plant out when you've got a nice big plant.




Gardening on the wild, windy west side of Dartmoor. 



  • Pink lilyPink lily Posts: 175

    thanks Lyn, I didn't realise you could bury as much of the stem.  and thanks for the pictures, they helped me confirm which of my seedlings are actually cosmos.  I forgot to label everything  this year image AGAIN! 

  • PageZPageZ Posts: 87

    I have leggy cosmos in a small pot at the moment. I am thinking if I can transplant them into the ground directly this weekend rather than potting on? I have limited space on the windowsill (too many other plants) therefore do you think the shortcut will be ok?

  • LynLyn Posts: 23,190

    If you do that Page, they won't be there tomorrow, you have to keep potting them on until you get a nice sized plant, the slugs will eat them and it's too cold at nights. You need to keep picking out the middles until you get a bushy plant.

    of course, it's entirely up to you what you do, it's just my opinion.

    you can curl them up Lily, they will grow even stronger.

    Gardening on the wild, windy west side of Dartmoor. 

  • eddie3eddie3 Posts: 81

    Have not been able to get my cosmos to germinate this year. Tried new seed and new compost. Failed. Other seeds seem OK. There's always next year.

  • Janie BJanie B Posts: 948
    Just bumping these useful pics up to show what to do with leggy cosmos... I may not be the only one asking this question...! Thanks @lyn!
  • LynLyn Posts: 23,190
    Thanks Janie, no doubt we will have the same questions from people who have sown them too early and they’re now leggy,.
    they germinate so quickly there no need to sow then before 1st April, Monty Don sows on the 1st June and has flowers right through autumn. 
    Gardening on the wild, windy west side of Dartmoor. 

  • debs64debs64 Posts: 5,114
    Thanks for that Lyn cosmos were on my list for today but now I will wait and sow something else. 
  • guttiesgutties Posts: 224
    @Lyn, could you do the same for Zinnias too (ie curl the stem and plant them deeper so just leaves are showing)?
  • LynLyn Posts: 23,190
    Haven’t done that with Zinnias, if yours are leggy now you could try, but they can’t be planted out until the end of May ish so they’ll be leggy again by then. 
    Make a note of when you sow the seeds, then next year sow 3 weeks later.
    i won’t be sowing zinnia fo at last another week. 
    Gardening on the wild, windy west side of Dartmoor. 

  • guttiesgutties Posts: 224
    Thanks @Lyn.  Yeah, this is my first year sowing seeds, so it's definitely a case of trial and error!
    I sowed Zinnia, and the Cosmos, 2 weeks ago today; the Zinnia germinated in 8 days and the Cosmos in 3.
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