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Growing Dahlias from seed with wildly different results

MJ-JJMJ-JJ Posts: 20
in Problem solving
I'm growing my GW dahlia from seed, using biodegradable and conventional pots, this is the outcome of treating them the same - same water amount, same conditions.  Can anyone advise what has gone wrong?  Do I need more water or less in the biodegradable pots?

Posts

  • punkdocpunkdoc Posts: 15,039
    Try feeling the soil, it is very difficult to tell without actually being there.
    How heavy are they compared to the plastic pots, that always gives you an idea about how well watered they are.
    How can you lie there and think of England
    When you don't even know who's in the team

    S.Yorkshire/Derbyshire border
  • BiljeBilje Posts: 811
    Mine are much smaller than yours, all in fibre pots. Those pots dry out very quickly so need to be side by side in a deeper container, as the plants grow the fibre needs to be moist so the roots can grow through. Also I'd suggest splitting the two in one pot. I'd als say compost to almost the top of either type of pot.
    i do realise neither of my observations help you, have you recently transplanted the seedlings? If so maybe the ones in the fibre pots weren't very robust. Dahlias hate to be too wet, they rot easily so moist compost but not wet.
    Hope you get more helpful help.
  • clarke.bruntclarke.brunt Posts: 215
    edited March 2021
    Well those on the left (i.e. in the biodegradable pots) are clearly wilted, so they aren't getting water up the stem and into the leaves (to keep them 'inflated'). That can either be because the soil is dry (like very dry, not just 'a bit' dry). Or it can be that the stem has rotted at the bottom ('damping off disease'), so the stem isn't capable of transporting water any more - more likely if it was very wet. The former is fixed by watering; the latter is fatal.

    Watering should never be by a particular amount of water, or a particular interval. It should be more like waiting until they're getting dry (by appearance of the soil, or the weight) and then giving a good watering until excess water drains through.

    Other things being equal, the bio-pot would need more water, as it's going to evaporate through the sides, whereas it isn't with a plastic pot.

    I'm assuming you haven't recently transplanted the wilted ones. Plants will sometimes need a bit of extra care after transplanting (like putting a propagator lid or a plastic bag over them top reduce water loss from the leaves) as the root disturbance will reduce their ability to take up water until the roots get going again.
  • FireFire Posts: 19,096
    edited March 2021
    Plastic pots keep water in better as are not permeable. An interesting test to demonstrate the principle.
  • KiliKili Posts: 1,104
    Looking at the outside of the biodegradable pot it looks dry.Poke your finger down to the bottom of the pot and see if the peat is wet or dry. If its dry give them a good soak. If its wet place the bottom of the pot somewhere its likely to dry out. As has been said if its rotted below there for dumping.

    I do mine in plastic trays (See below) which are not to deep so I spray each cell in the tray individually depending on if its wet or dry as they require water at differing rates depending on how advanced each plant is.



    Good luck hope they survive for you.

    'The power of accurate observation .... is commonly called cynicism by those that have not got it.

    George Bernard Shaw'

  • MJ-JJMJ-JJ Posts: 20
    edited March 2021
    This is great feedback, thank you everyone! They are very dry, so will give a good soak and hopefully can save them.
  • MJ-JJMJ-JJ Posts: 20
    One has recovered! But the others still very wilted, won't give up yet though.
  • MJ-JJMJ-JJ Posts: 20
    An update- two were saved and coming along beautifully. When is everyone planting out?
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