Damping off! **Please** help!

I started my affair with gardening last year, we bought one of these cheap plastic greenhouses and starting growing various plants from seed. I then met damping off and had a terrible time with it. I read all I could find about damping off and this year I set out on a mission:

We bought a new cheap plastic greenhouse, new seed trays, new everything, new seedling compost, etc. We went hygiene mad.

I've painstakingly sown my seeds at a good distance apart from each other to avoid overcrowding,

I've provided good drainage using grit and mixed it in with my compost,

I've watered from below as sparingly as I can,

I've sprinkled grit on the surface of larger seeds,

I've opened the greenhouse most days to allow good air circulation,

I've used cinnamon on the surface,

Nothing seems to have worked and my seedlings are suffering and dying because of damping off again, the ones that haven't yet died I'm so scared they will end up dying anyway image

I was wondering if anyone else can advise what I should do?? (I've removed the offending pots and I still have some other trays in there which don't seem to be affected... yet).

Should I cut holes/flaps in the side of the greenhouse to improve air movement?

Has anyone had any luck with charcoal?

Should I do a deeper layer of cinnamon?

I didn't want to use chemical, but now I'm starting to be open to the idea to avoid the heartache, can anyone recommend a brand which I can spray the surface with?

What else can I do? This is driving me mad!

I have 0 budget to buy anything better than this cheap greenhouse and my windowsill is full. Please help!


  • Sprig2Sprig2 Posts: 75

    I have had the same problem in my cheap plastic poly tunnel this year. I got sick of it in the end and 2 weeks ago took everything out and put it on the patio outside. The seedling have never looked better. I just think I could not get enough ventilation in the tunnel as it only opened at one end. Where in the country are you? Maybe your seedlings could go outside too.

  • DovefromaboveDovefromabove Central Norfolk UKPosts: 42,870

    SchlumpfLouise - don't lose heart image

    What sort of seeds/plants are we talking about here? 

    I don't have a greenhouse, only a wooden version of what you have - I've not started any frost-tender seeds yet as in the past I've found that the contrast between night and day temperatures has been too much for them - I plan to sow my tomatoes, courgettes etc this week - they'll start on the kitchen and diningroom windowsills and it's not until they're too big for those spaces that they'll go out into the mini-greenhouse.  

    I find that because of the confined space and restricted air-flow  in a mini-greenhouse the variation in temperatures is much greater than in a conventional greenhouse and you cannot get the same results.  The mini-greenhouse is more useful if used more like a cold-frame than a greenhouse.


    Gardening is cheaper than therapy, and you get tomatoes. 
  • scrogginscroggin Posts: 2,050

    Echo what Dove has said. There is a huge temperature differential at this time of year in a small confined area like a small greenhouse.

    I have polytunnels but I only use them to frost protect seedlings once they have been established indoors. I find that once they are growing strongly they will be fine.

  • Forester2Forester2 Posts: 1,478

    Ditto Dove & Scroggin.

  • Thank you all for the fast responses. I'm in the West Midlands (city centre, Wolverhampton) and I'm growing pretty much everything except veg! Most seeds have been sown with wildlife gardening in mind (trefoil, cornflowers, snapdraggon, wallflower, verbena, etc...), but there also a few pretty things in there like various poppies and morning glory and my vast array of sweet peas! There are also a few perennials I'm trying from seed.

    I haven't really got anywhere indoors to start seedlings. Also, in a rented Victorian house, I'm not sure the temperature variation wouldn't match the greenhouse!

    So I think I'm reading from this to not try to argue with nature and just wait and sow when conditions are right outside?

    Should I take the plastic cover off the greenhouse (gradually over the next week or so) and then only put it back on if frost is forecast? I'm realy very grateful of your replies....

  • DovefromaboveDovefromabove Central Norfolk UKPosts: 42,870

    Sweet peas can be hardened off and put outside - mine have been planted out with no protection for a while - and you can direct sow some more now image

    All of the rest, with the exception of Morning Glory, are hardy and could be sown direct outside.

    I would keep the greenhouse 'door' wide open in the daytime and 'ajar' at night  - that will suit everything except the Morning Glory.

    For the Morning Glory I'm afraid it's far too early - they really don't like cool weather and won't grow - if they are started off in the warm and then put outside in the cool the leaves turn white.  I've not even sown mine yet and probably won't do so until the end of  April/beginning of May.  I'll then keep them indoors on the kitchen windowsill until mid June when they'll be planted outside.  If I were you I'd get another packet of Morning Glory seeds and start another lot off on the kitchen windowsill (I used to have a Victorian terrace with a north-facing kitchen window - it is possible image)  If both lots succeed you'll have double the Glory!!!




    Gardening is cheaper than therapy, and you get tomatoes. 
  • After last year, I've only sown a few seeds out of each pack, just in case this very thing happened, so thankfully I've got plenty of seeds of everything still left! 

    I did have to plant out some of the sweet peas already which were ones Monty told me to sow in Autumn, they had to be planted out! The other sweet peas in there are maybe 4" and I've moved some of them to a sheltered spot next to the house about a week ago and they are holding up (I did search the forums first and found many people said they were quite hardy). Even some of last year's sweet peas are still going thanks to the mild winter!

    I will take your advice with the Morning Glory and sow them much later, however my windowsill is full with other seedlings and plants already! Quite happy with my litle Callicarpa bodinieri seedlings on there!

  • I started this thread a couple of weeks ago with just this problem in mind. http://www.gardenersworld.com/forum/talkback/damping-off/283320.html

    The problem with these plastic constructions is that they provide wild fluctuations between night & daytime temperatures and this is responsible for much of the problem. 


  • ommthreeommthree Posts: 295

    How big do people reckon seedlings have to get before they're safe?

  • DovefromaboveDovefromabove Central Norfolk UKPosts: 42,870

    Ommthree image

     It all depends on what type of seedlings ....

    Gardening is cheaper than therapy, and you get tomatoes. 
  • ommthreeommthree Posts: 295

    Well, to pick a few at random….. tomatoes, chilies, basil, parsley, marjoram, cornflowers.

  • HI I just wanted to give an update on my damping off!

    Firstly thanks to all of you for your advice, I have learnt ventilation is key! Since keeping a focus on ventilation I have had no further issues, all my second sowing of seedlings are off to a flying start, even some of the first batch which I removed to a sheltered position have survived!

    The greenhouse cover gets practically removed when it will be a good day, covering the top when rain is predicted and is zipped up on one side during the night unless it will be very cold when I zip up both sides. Also, in handling the cover I've made some accidental ventilation holes which I think may have been beneficial!

    You can't believe how happy I am now to come home every day and find success rather than disappointment!

  • Busy Bee2Busy Bee2 Posts: 1,005

    That's brilliant news, given how fed up you were a month ago.  I shall be planting a lot of seeds later next year after my experiences this year.  By now, your main worry is a late frost, but provided you can give shelter for that eventuality, hardening off is in full swing in May and by June we can still things out with confidence!! 

  • Carol 13Carol 13 Posts: 30

    Slightly off topic here but related, I've got some cucumbers in my gh they were grown inside and planted in the gh when they were too big for windpw sill they looked fine until about a week ago when some started to wilt, I've noticed the stems near the compost look to be rotting is this damping off too? The gh is unheated so the temp swing is quite big!! Too cold of an evening perhaps?? 

  • We are basically city centre Wolverhampton and all the seedlings are right next to the house so I'm not overly worried about frost (famous last words!!) It's the slug that's done in my wallflower fire king and my sea lavender that I'm most worried about now!


  • Busy Bee2Busy Bee2 Posts: 1,005

    Carol, my old gardening book says that cucumbers should be planted at the top of a mound to avoid water gathering round the stems, and you have to make sure it drains away when you water.  Also, that everyone thinks cucumbers need more water than they do, so watering should be regular but not excessive.  Whether or not at this stage you could earth them up a little further I don't know.  They tend to sulk anyway when you transplant them, even the slightest disturbance of their roots will make them look sorry for themselves, but they do perk up. 

  • FairygirlFairygirl Posts: 19,692

    Glad you've resolved the problem SLouise. Up here we're resigned to the fact that sowing a lot of stuff  has to be done later  unless you have a conservatory or a proper greenhouse. I sowed some cornflowers outside directly into pots a few weeks ago, just in the shelter of the house wall. They're about 2" high now and growing well. I only use the plastic greenhouse thingy for my tomatoes, which are on the kitchen windowsills just now, and a few pelargoniums. Not much else. As others have said - it's the difference between night and daytime temps that causes a lot of problems with early sown stuff, and then ventilation.

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