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Seed Sowing

I would like some advice please on failure of small seeds to germinate. I seem able to get some to take by sowing in trays of seed compost and covering with a sheet of polythene eg leeks,lettuce,cosmos,zinnia,but seed of aster and larkspur sown in a similar manner did nothing. Are there any different ways of ensuring seed germination for these tiny seeds. Am i covering them too long ,or are they too wet, or not warm enough. They are in an unheated greenhouse. Any advice would be welcome . Many thanks 


  • Almost certainly they are too cold.  Obviously the other points you mention are also possible, the seeds could be past their sow by date too but given you've had some success it's unlikely.

    Do you have space to bring them indoors?


  • Kitty 2Kitty 2 Posts: 5,150

    Hi Cathryn, nothing wrong with sowing seeds in an unheated greenhouse although they may take a little longer to germinate than ones grown indoors.

    How long ago did you sow your seeds?  I did mine 9 days ago and have cosmos, zinnia, aster and lettuce all popping up but nothing yet from my larkspur as they take a little longer to get going. 

    We have a thread on seedlings with photo's of our progress if you fancy having a look at how others are doing, you're welcome to join in.  "Watching seedlings grow 2016"

    Kitty (aka Kathryn) image  


  • CeresCeres Posts: 2,272

    Try starting them off on a windowsill indoors. Its a bit cold for a lot of things to germinate in a cold greenhouse at present. I start things off indoors then move them to the greenhouse during the day until it is warm enough for them to take the nighttime temperatures, by which time the plants are usually butch enough to look after themselves.

  • Kitty 2Kitty 2 Posts: 5,150

    Larkspur is a hardy annual which can be directly sown outdoors in flowering position.

    If the greenhouse was warm enough for the other half hardy's to germinate (cosmos and zinnia) it should be ok for the asters. My packet states 14 to 21 days so maybe there's still time for them to pop up.

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