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Seedlings not growing on

LatimerLatimer Latimer, BuckinghamshirePosts: 790



Good morning everyone!

I showed some seeds in trays maybe 2 weeks ago. I was happy enough to see the seedling appear but they don't seem to be doing much since they did.

They've been kept in a plastic sheet greenhouse. I try and get the front of the greenhouse open most days though sometimes I forget or I'm too busy. 

Initially I'd water them with a fine rose, checking if they were too dry by the weight of the tray. I've since transferred them onto trays of wet gravel.

Should I be concerned or is it normal for the growth to slow down?
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  • DovefromaboveDovefromabove Central Norfolk UKPosts: 82,089
    edited May 2022
    The compost looks too wet to me. They’ve hardly got any roots at that stage so can’t take up much moisture  … they need ‘damp’ compost … not ‘mud’. 

    If you don’t open the greenhouse they’ll absolutely ‘cook’ on sunny days … as far as I can see there’s nothing there that needs high temperatures. If you’re  not certain about opening the greenhouse every morning then I’d leave it open overnight unless frosts are forecast. 
    “I am not lost, for I know where I am. But however, where I am may be lost.” Winnie the Pooh







  • FairygirlFairygirl west central ScotlandPosts: 48,907
    I agree. The most important things for seeds to germinate and thrive are free draining compost, and temps which aren't swinging wildly from one extreme to the other.
    The plastic greenhouses get hideously hot - even on days with mid teens temps. The also provide very little warmth overnight except in hotter temps, so that's where you get extremes. 
    Ventilation is vital.  
    It's a place where beautiful isn't enough of a word....


  • LatimerLatimer Latimer, BuckinghamshirePosts: 790
    Thanks @Dovefromabove and @Fairygirl I'll definitely start leaving it open, I'm in London area so although it's been dropping down to 4deg recently I think all risk of frost has passed. Would leaving one side of the front unzipped at all time be enough ventilation?

    Also, do they look salvageable? Or should I sow some more?
  • LynLyn DevonPosts: 21,134
    Lobelia is very slow growing, if you want lobelia plants for this year, I would buy some.
    To sow those, you just sprinkle them on the compost,  don’t cover them with anything,  they need light to germinate and grow on. I don’t think there any point in sowing more now.  Start again earlier next year,  in your kitchen.

    As others have said,  they are far too wet,  I never water seeds/seedlings,  I put them I damp compost then use a spray mister bottle.

    Pansies and violas like to germinate in cooler temperatures,  I sow mine about end of September in the GH, prick out, then pot on in the Spring. I’m about to plant mine out now. 

    I cant see the label on the 2nd photo, but the soils looks very bulky and claggy,  I wouldn’t put seeds or seedlings on wet gravel. 
    Gardening on the wild, windy west side of Dartmoor. 

  • FairygirlFairygirl west central ScotlandPosts: 48,907
    I never used the plastic growhouses [when I had them] for seed sowing, apart from sweet peas. They're not great, for the reasons I mentioned earlier. If I sow seed that needs protection due to their hardiness, I sow, and keep them,  in the house until they're at a suitable stage for going outside. Wet cold is always worse than dry cold  :)

    When you're starting seeds, having a good amount of Perlite or grit mixed in helps with preventing waterlogging. About 50/50. If you can let those dry out a good bit, they might be ok. The violas will be more tolerant to moisture.
    I'd sow more though.  :)
    It's a place where beautiful isn't enough of a word....


  • LynLyn DevonPosts: 21,134
    I don’t think there’s any point in sowing more lobelia.
    Perlite is ok mixed in with the compost,  if you really want too, but not on the top of lobelia. (Or any tiny seed) 
    Best thing is not to let the seeds get too wet. Spray mist not watering can.
    Gardening on the wild, windy west side of Dartmoor. 

  • DovefromaboveDovefromabove Central Norfolk UKPosts: 82,089
    Latimer said:
    Thanks @Dovefromabove and @Fairygirl I'll definitely start leaving it open, I'm in London area so although it's been dropping down to 4deg recently I think all risk of frost has passed. Would leaving one side of the front unzipped at all time be enough ventilation?

    Also, do they look salvageable? Or should I sow some more?
    I’d totally unzip it and tie it back so one side is completely open. Just close it up if frost is forecast which is unlikely in your area now. Just keep an eye on your local weather temps on an app or the tv weather chaps. 
    “I am not lost, for I know where I am. But however, where I am may be lost.” Winnie the Pooh







  • FairygirlFairygirl west central ScotlandPosts: 48,907
    That looks more like Vermiculite on the top. I agree with @Lyn though, it isn't always helpful to have something on top, especially with those really tiny seeds. Misting is by far the easiest method. I even do that with bigger seed. 
    Some info suggests Vermiculite holds water too. I always use Perlite mixed with the compost I use. 
    It's a place where beautiful isn't enough of a word....


  • LynLyn DevonPosts: 21,134
    It is vermiculite, Fairy,  I’m not keen on it,  it stays wet,  or is that just in my damp area? 
    Gardening on the wild, windy west side of Dartmoor. 

  • LatimerLatimer Latimer, BuckinghamshirePosts: 790
    Thanks once again @Lyn @Fairygirl & @Dovefromabove

    I can see a multitude of errors!! 😂

    1. I used vermiculite not perlite which i now understand, from googling, holds much more moisture than perlite. Covering the seeds in that has probably resulted in them being far too wet.

    2. Sitting them on the gravel has kept them too wet.

    3. The plastic greenhouse is extremes of temperature if not opened daily. I tie it back as suggested.

    Does an untreated glass greenhouse go through the same temperature extremes as the plastic ones if not properly ventilated? I'm assuming for the less hardy seedlings you'd need a heated greenhouse? 
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