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Cold stratification of seed?

LeadFarmerLeadFarmer Posts: 1,500
in Plants
Anyone regularly cold stratify seeds?

I sowed some Eryngium bourgatii (sea holly) seeds in my cold greenhouse at the beginning of January, as per the instructions. As there has been no germination the instructions suggest placing the seed try in the fridge at 4 degs for 2-3 weeks.

I thought the weather had been cold enough lately, but maybe I do need to do the next stage in the fridge? Or maybe they now need some warmth?

Anyone have good success with doing this with seeds that require it?

Posts

  • Pete.8Pete.8 Posts: 11,340
    I grow them from seed that I usually sow in pots around October.
    I cover the compost with grit and leave them in a shady, sheltered site outside overwinter.
    I see germination usually around March/April, and some still pop up many weeks later.
    I think you need to give them quite a bit more time to show.

    Billericay - Essex

    Knowledge is knowing that a tomato is a fruit.
    Wisdom is not putting it in a fruit salad.
  • LeadFarmerLeadFarmer Posts: 1,500
    Thanks, maybe I need consider whether to leave them in the greenhouse or bring outside.
  • KeenOnGreenKeenOnGreen Posts: 1,831
    I used to leave our Eryngium seeds in pots outside, so they get full Winter exposure. Greenhouses are much milder environments, and can get quite warm on sunny Winter days. As @Pete.8 says, it would have been better to plant them in the Autumn.

    I would get them out of the greenhouse now, and as Pete says, put them somewhere sheltered, but so they still get exposure to the cold. 

    I have never bothered with the fridge method, too much of a pfaff.
  • fidgetbonesfidgetbones Posts: 17,618
    I would put them outside for a few weeks. Just cover the surface up with a slate or chicken wire so the birds don't scratch it up.  Bring them in at the end of Feb and they should germinate in March.
  • Cambridgerose12Cambridgerose12 Posts: 1,134
    Have used the fridge method successfully but only for Cyclamen.

    If you've given yours the suggested time period in the fridge, you should take them out after that--the biochemical mechanisms for germination will have been triggered. Let them stay outside from now on and wait and see. If nothing appears in March/April, you could still keep trying but this time leaving the pot outside overwinter.

    Good luck! I am trying outdoor cold stratification with tree seeds this winter. Curious to see what comes up...if anything.
  • thevictorianthevictorian Posts: 1,279
    I leave them outside and let nature take care of when they sprout as well. I have quite a lot in my garden and the selfseedlings mainly begin to grow in march/April but I get a few coming up even into autumn. 
    Eryngiums are supposed to be quite slug resistent, and the mother plants are when they reach are decent size, but around here the seedlings are devoured by slugs/snails quickly so I'd advise keeping them somewhere you can easily check daily. 
  • LeadFarmerLeadFarmer Posts: 1,500
    Thanks for the advice, I shall move them outside and cover them.
  • LeadFarmerLeadFarmer Posts: 1,500
    I ended up moving the seed trays with their clear plastic covers outside, placed on the ground by the greenhouse. About a week later I noticed two of the seeds had germinated. Feering the frosts would kill the little shoots I have moved them back inside the greenhouse.
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