Allotments 4 All
Produce => Under Glass => Topic started by: Garden Manager on April 04, 2015, 10:39:43
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Been getting this problem with increasing frequency recently. Seedlings get pricked out into fresh compost and clean pots/ trays, are kept damp but not wet and given gentle bottom heat to stimulate root growth. Nothing done differently from previous years. Then without warning seedlings start flopping over an looking sorry for themselves. They haven't dried out either but don't dare water and make things worse. I am rather baffled and don't know what to do.
As I mentioned above i have hardly had any problems like this in the past, now I am second guessing myself when it comes to seedling aftercare!
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Photo might help?
I've had what I initially thought was damping off and turned out to be slug/snail damage instead. They aren't the same, but damping off was my first reaction as I hadn't had it before and thought that was the only possible outcome ...
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not wet and given gentle bottom heat to stimulate root growth
What is the general atmosphere temperature?
I have this theory that bottom heat and ambient heat has an affect at soil level i.e. where the damping off occurs.
My theory is at this level you have two extremes of temperature i.e. the soil temperature and the atmosphere temperature where you inadvertently create this situation.
So depending upon the plants I am growing, I either give them no bottom heat, and for those that are on bottom heat I cover them with a propagator / seed tray cover.
At least this way the plants are surrounded by a relatively consistent temperature.
Having said that I keep my greenhouse at around 40°F (4°C)
But as I said it is only a theory!
What do you all think?....Tg
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Seedlings raised in heated propagator then onto a heat mat once pricked out. Did get covered with a lid overnight but this attracted too much condensation so they arenow left off. Seed pots in propagator are now ventilated during the day as they hav e started to come up. Considering discontinuing heat completely and ventilating 24hrs. Located in double glazed conservatory which is gently heated at night.
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The only seedlings where I have damping off problems are brassica. In the conservatory damping off, in the greenhouse not. It is colder and brighter in the greenhouse that is the only difference I can see. I just don't sow brassica in the house or in the conservatory any more. :wave:
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I have a theory that they need sunshine just at the point that the cotyledons open. I have taken to putting them under my SAD lamp if the sun does not put in an appearance.
No sun and I find they go leggy and damp off. I try and sow brassicas a few days before there is sun forecast but it is obviously not reliable.
It looks promising later this week, so I am going to start another batch today.
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I agree with Digeroo, light is really important.
I tend to overwater and so I usually end up with mould and some of my seedlings die. I'm just terrible at judging when to water!
But this year everything's spent time in my new makeshift light boxes and even when the compost's soggy there's no mould. Couple of little mushrooms, but they don't seem to cause any problems.
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I have a similar problem with onion seeds........grown ok in the greenhouse, but have now started to wilt and die, :BangHead: I have no idea what caused this or how to remedy it.......any ideas!
Paul
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WElcome to A4A Beelucky2.
Damping off is caused by a fungus infection. But how to stop it is much more difficult. Fresh compost and not overwatering help. But sometimes it is quite a mystery. I have found that tap water is better than butt water.
I thought yoghurt or aloe vera might help but when I tried it the control batch was fine as well even though I did everything to them I thought was wrong.
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What about some cheapy homebase anti-mould spray? Never tried it but I just thought I'd throw it out there.
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The alternative approach is to sow seeds straight into garden soil (with or without some added sand, leafmould, garden compost etc.) rather than commercial sterilised seed compost. The reasoning is that the wide range of bacteria, fungi etc. present in soil compete with and restrain the pathogenic fungi that cause damping off, whereas in a sterile mix the pathogens can spread without restraint if they get in (from airborne spores, dust, soil particles, dirty water etc.). There are other advantages to using soil as well: it's free, you can use as much as you like, there's no use of environmentally damaging ingredients such as peat, and it's the same as the soil the plants will be growing in after transplanting to the garden (I guess this might reduce transplant shock). You also don't need to worry about keeping eveything sterile.
Soil also washes off the roots very easily when transplanting (mine does, at least), making it easy to separate out the roots of individual seedlings. Much better than tearing apart peat based compost and damaging the roots.
The main disadvantages I've found have been the number of weed seedlings that you can get coming up, and the potential to introduce small slugs that eat the seedlings. The first problem is less important with larger seeds and with quick germinating seeds, and obviously if you know what the seedlings are meant to look like. I think covering the soil with a layer of sand after sowing also reduces weed germination. Slugs can be looked for at night if necessary (I don't use pellets), although they haven't been that big a problem.
For mycorrhizal species (e.g. onion family), sowing in earth should also be beneficial in containing the correct fungi.
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The alternative approach is to sow seeds straight into garden soil
Wouldn't work well for me I'm afraid :(
- heavy clay soil, impossible to get it dry / cultivated into a seed bed early in the year
- Few daylight hours early in the year, so good weather coinciding with time off work etc. is rare
- If sown direct then the weeds germinate too and they, by definition!, are more efficient / vigorous than the vegetable plants so time needs to be spent hand weeding the seed rows
- Seedlings are at the mercy of the weather - a cold spring and harvest can be delayed etc.
The advantages that I find in raising plants and then planting out are:
- Can sow on exact date I want. After dark / weather not a problem for sowing indoors of course
- Can start earlier than would be possible outdoors - i.e. where outdoor soil temperature is important, such as good germination of parsnips
- Can raise exactly the number of plants I want. For example, Cauliflowers don't "stand" long after their heads are ready, so I sow 4x pots every fortnight (during the season) which means they come ripe at about the rate that we eat them
- After planting out the plants have, say, a 6 week lead over the weeds so by the time the weeds need hoeing the plants are a decent size and weeding is easier, plus the more leafy varieties are already starting to shade the weeds out by then
- When appropriate at planting-out the plants can be set deeper - e.g. Brassicas / Tomatoes. For Clubroot plots plants can be potted-on to, say, 5" pots and grown on significantly which helps a lot to offset the Clubroot
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Wouldn't work well for me I'm afraid :(
Sorry, you've misunderstood me - perhaps I should have been clearer. I meant using regular soil in pots or seed trays (e.g. for starting seeds in the greenhouse) as an alternative to bought potting compost. I wasn't talking about sowing seeds straight into the ground.
For instance, I've just been planting out a load of leeks and onions that I sowed in 6" pots in February, using garden soil topped with a layer of sand - germinated in a propagator then grown on in the greenhouse. The % germination was very high and subsequent seedling mortality was essential zero. Transplanting has been very easy because the soil washes away cleanly after a brief soaking, so minimal root damage. Separating the roots of peat-grown plants is much more difficult.
Obviously everyone's garden/allotment soil is different, so what works for me may not work for someone else with different soil. Pure heavy clay might be tricky, but it's worth experimenting though (perhaps a soil / garden compost blend). I recently collected a load of council green waste compost (very cheap in bulk), so I'm trying a layer of that to cover seeds sown in pots/trays containing earth - mainly to reduce the amount of weed seeds coming up. Essentially:
1. Soil sieved from garden
2. Mixed with a bit of homemade leaf mould (optional)
3. Pots/trays/modules filled with the sieved soil/mix
4. Seeds sown on top (or slightly buried)
5. Covered over with a layer of sand / council green waste compost
6. Watered from below
7. Placed in propagator/greenhouse to germinate
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Wouldn't work well for me I'm afraid :(
Sorry, you've misunderstood me - perhaps I should have been clearer. I meant using regular soil in pots or seed trays (e.g. for starting seeds in the greenhouse) as an alternative to bought potting compost. I wasn't talking about sowing seeds straight into the ground.
Ah!, my apologies.
Pure heavy clay might be tricky
Sadly!
However, I do do something similar which does work for me:
I replace the soil in my greenhouse borders annually ("annually" is probably not strictly necessary). I replace it with 50;50 compost heap and rotted manure. My compost heap is best described as "rough"!! but Tomatoes etc. are happy with it - it holds plenty of moisture.
But, when I take the "soil" out the following Autumn it is beautifully cumbly compost/loam. I use that to pot-up things that I over winter - Cannas and Dahlias and the like, and for other potting needs where ultra-fine is not required.
I'v never been brave enough! to use it for seed compost etc. but I re-use my seed compost - but I suspect mixed with Sharp Sand or Perlite it would be fine. Instead I re-use repeatedly John Innes Seed Compost - the one I have is a very sandy loam, which falls easily off seedlings when pricking out, as you describe. I sow in seed trays and then just tip the seed compost into a bag when I have pricked out, then sieve that (through a fine sieve) to remove any roots. I make sure it is reasonable damp, but not wet, and put in Mrs K's largest Pyrex bowl (don't tell her!!) and microwave for 10 minutes and let it cool down by itself. I hope that the moisture turns to steam and spreads through the whole batch.
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Just came across this old post ,what with sowings about to start thought I would say that ive heard that cinnamon sprinkled over the top of the compost when sowing and transplanting will stop damping off Have any one heard of this or even tried it
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Using the theory that seedlings tend not to damp off when summer sown when warmth and particularly light levels are high I find that by placing early sown seedlings under grow lights at the first signs of germination damping off is drastically reduced if not eliminated altogether.
The seedlings don't get drawn either.
Just another approach to consider. :happy7:
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Just came across this old post ,what with sowings about to start thought I would say that ive heard that cinnamon sprinkled over the top of the compost when sowing and transplanting will stop damping off Have any one heard of this or even tried it
Thanks for renewing this discussion BT2. Some interesting ideas. Rightly or wrongly I always thought the main cause of damping off was sowing seeds too thickly. Perhaps this helps provide the right conditions for fungus to grow.
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I've found putting a thin layer of vermiculite on top of the compost seems to help in unheated propagators.
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I have used cinnamon on my seedlings to stop mould forming on the soil surface and it did work ... cinnamon definitely inhibits mould growth and damping off is caused by a type of mould.
However ... it also caused my seedlings to stop growing and look very sickly indeed ... So I'm not sure it's the right thing to use in this case.