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Cosmos from seed

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I'm growing some Cosmos from seed in a heated propogator. They've raced on ahead of all other seeds and after just a week are now standing around three inches tall. The stems are quite strong though.Is this natural for these tall growing plants or are they destined to become leggy right offs? The Dahlias and Tagetes in there are doing quite nicely. Advice greatly appreciated.

On plant Cosmos



I don't know the answer, but thoght it might make you feel better when i say that mine have done exactly the same.

Mine germinated quickly, they are very tall and weedy looking as if too much heat and light. I havent anywhere cooler than the present north facing conservatory to move them to...unless I pop them into a cold frame but that seems too chilly doesnt it?

I'll be interested to hear what others say!

19 Mar, 2008


I grew these last year and found that I had to prick them out much sooner than all the other seedlings. They were fine once I'd done that (in an unheatedgreenhouse by the way) and I ended up with so many that I was practically begging people to have a few! I am about to sow a different type - red/orange in colour and not as tall as the usual ones. I am looking forward to seeing how they do!

19 Mar, 2008


I have also just sown some of the `Cosmos bipinnata` in a cold greenhouse, I think they should be ok although I too wasn1t sure if it was too cold, but I`m sure I grew them the same last year.
I got the seed from the RHS site in January along with lots of other seeds which I am trying, does anyone else take advantage of the seeds availbale from RHS?

19 Mar, 2008


Yes - I got some for the first time this year. I haven't planted any yet. We will have to compare notes as to how we do.

19 Mar, 2008


My cosmos have also shot up. think this is normal - they do this every year! I don't think you need to keep them in the heated propagator now they are up and growing - put them where they will get plently of light (so they don't have to stretch for it) and just keep them frost free. Mine are in an unheated greenhouse, but I do bring them indoors when the nights are frosted.

19 Mar, 2008


Thanks everyone. Your replies are very reassuring. I'll keep you informed of progress.

19 Mar, 2008


Just this weekend (in U.S.) I planted Cosmos seeds, have never before. We live in a residential neighborhood and they are planted around our shed. I was told by a fellow gardener I may be sorry. According to him, Cosmos belongs in fields, they are easily spread through the wind and will be coming up everywhere!?! I'm afraid my neighbor won't appreciate this (nor, I'm thinking, will I ...:)

28 May, 2009

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