Struggling seedlings, what can I do!?

Discussion in 'Edible Gardening' started by Rob Hems, Apr 24, 2025.

  1. Rob Hems

    Rob Hems Apprentice Gardener

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    Hi folks. New to the forum and not as experienced as I thought I was in growing tomatoes and beans, I'm somewhat crestfallen having decided to make a bigger than usual effort this summer. Sorry this is a bit long.

    About 4 weeks ago I planted what I thought was plenty of tomato seeds and ample runner and dwarf beans for my needs. I expected to be only picking out the strongest plants as I only have limited space (growing in big pots on the patio)

    So, all was well, everything germinated really quickly in a small propagator and modules, using seed and cutting compost. The runners and dwarf beans continued to grow, I re potted individually. Some of the tomatoes were starting to show the beginnings of true leaves but not making any further progress. I thought I'd better prick them out and repot.

    Now the problems.
    1. The runners are extremely fragile. Leaves are like wet tissue paper and stalks kink easily, presumably being kinked making them a useless prospect(?) A few had leaves curl up and were disposed of. I'm left with no usable plants. I've resown in the propagator and would like to avoid the same mistakes - if I can identify what I've done wrong, that is!
    2. The Dwarf French beans look reasonably healthy but refuse to grow, two leaves each only, they haven't changed at all in around 10 days. A couple suffered curled leaves and were binned.
    3. The tomato seedlings appeared to be ok for a couple of days after potting but 5 days on none are showing any growth and 1 or 2 are dying each day, I'm running out :(

    All were grown from seeds purchased this year and well in date.

    I potted using growbag compost, I have a nasty feeling that this has something to do with the wholesale abuse I've caused. It's quite a coarse mix and I guess they may not like the balance of nutrients.

    I'd been conservative with the watering but increased when I noticed leaves curling, it didn't help.

    Everything is grown in the kitchen, in front of french doors in full sun for part of the day. No chance of hardening anything off, the slightest breeze or unfiltered sun will destroy what little is left!

    I had a very successful year with both beans and tomatoes a couple of years ago, the only obvious differences were using coco coir for germination and a GP compost for potting on. I had no clue what I was doing then and didn't manage to kill anything.

    Any advice or suggestions greatly appreciated.
    TIA
    RobH
     
  2. Allotment Boy

    Allotment Boy Lifelong Allotmenteer

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    Some pictures might help. The reasons could be many and varied. We have had very mixed conditions recently with dull days and cold nights. Tender plants need as stable conditions as possible. It may be that the growbag compost is too coarse with too much nutrition, the fragile roots of young seedlings may not be able to cope with it. Many peat free composts are quite coarse. Many growers now sieve all compost to remove any coarse pieces of bark etc and mix with sharp sand or small amounts of fine soil, to allow fine roots contact with soil particles. If the plants are thin and spindly then they are not getting enough light.
     
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    • JWK

      JWK Gardener Staff Member

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      I get the feeling you are overwatering, the compost needs to be moist not saturated. Have you got drainage holes in the pots or trays? And is there a way excess water will run off, they mustn't sit in water.

      Also getting full sun behind patio doors may well be cooking delicate seedlings. New seedlings would need shading of some form. Have you got a max/min thermometer to check?
       
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      • pete

        pete Growing a bit of this and a bit of that....

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        Compost is varying wildly, not sure what grow bag Compost is like these days but I've seen some that has the appearance and texture of coal dust.

        I think you are probably cooking the seedlings on sunny days.

        Also sounds like it's too warm even when it not sunny and the beans have grown very leggy.
         
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        • AnniD

          AnniD Gardener

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          Another thing with peat free compost is that it can appear bone dry on the surface, but is very wet underneath.
          If you can post some photos that may well help with any future advice :smile:.
           
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          • Rob Hems

            Rob Hems Apprentice Gardener

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            Thanks for the replies. I picked up some John Innes No.2 potting on compost this morning, I'll try transplanting anything that isn't dead by the time I get home tonight. Hopefully a second shock in a short period won't finish them all off.
            I'm pretty confident that I'm not overwatering, I have been guilty of this in the past and learned my lesson then. All pots have drainage and nothing is sitting in water. Compost is only slightly moist a couple of inches below the surface.
            The main themes seem to be over baking and poor root/compost contact. I'll have a think about where to relocate my victims :) I'm sure I'd read somewhere that as much light as possible was needed, I guess I've blurred the distinction between heat and light.
            There's not much left to photograph but I'll be sure to include some pics next time I go on a seedling persecution spree!
            Thanks, Rob
             
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            • CarolineL

              CarolineL Total Gardener

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              John innes no 2 has more food for potting on established plants. I would add some sand to make it "leaner" for seedlings.
               
            • waterbut

              waterbut Gardener

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              Add some perilite to help with drainage.
               
            • Rob Hems

              Rob Hems Apprentice Gardener

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              All noted, with thanks.
              I just don't understand why nothing is growing. I've seen other threads about seedlings 'frozen in time', this is what seems to be happening here but I can't see any useful information in any threads to get them going again.

              Also; 16 hours sunlight per day seems to be the requirement. If we happen to get 16 hours bright sunlight in one day, how on earth do I keep the temperature in the mid to high teens? Bright sunshine = mid twenties indoors.

              None of this makes any sense to me. Last time I grew tomatoes they just grew, no fuss, no issues, they germinated and kept on growing until they were viable plants.
              Cheers
              Rob
               
            • AnniD

              AnniD Gardener

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              When you last grew tomatoes, was it under the same circumstances (that is, were they treated exactly the same, by patio doors etc.) ?

              Seed sowing can be like Russian roulette at the best of times and the arrival of peat free compost seems to have exacerbated problems in that it is so variable. Is there any chance of a couple of photos, it would help. (I know your descriptions are very good :smile:).
               
            • waterbut

              waterbut Gardener

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              We have just had to buy tomato plugs from GC. My wife tried two different packets of seeds using the same system she has always used with success. One weedy plant grew out if all seeds planted.
               
            • Philippa

              Philippa Gardener

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              I tend to sieve all compost for sowing seeds and mix with perlite. I have also found that some plants this year ( notably tomatoes ) have not grown as quickly as expected. Make sure you don't sow too early, provide bottom heat, don't "over pot" and don't leave in full bright sun ( curling leaves is one giveaway ).
              You mention that your toms did well last time so have any of your sowing/growing on methods/medium changed since then ?
              As @AnniD says, the use of peat free compost and the changing weather patterns make things very frustrating.
              Good luck with getting some thriving plants :)
               
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