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Dahlia tubers

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  • oooftoooft Posts: 191
    Droning on a bit here but I always end up thinking of more questions.

    How warm is too warm for these starting in pots? Reason I ask is I'm keeping them in the conservatory now and it gets the sun in the latter half of the day so the temperature is knocking on 30 degrees. Don't really have anywhere else I can put them that's guaranteed frost free, not too warm and with light.

    Was thinking of the shed but not much light and can get warm itself.

    I've got a cheap cold frame but it won't do much if there's freezing temperatures overnight. 
    Keep asking questions. I've learned loads from reading other people's questions and the answers they received. Over 26 or 27 degrees isn't great. Are you able to leave the internal doors of the conservatory opened during the day? I find that can reduce the temp in the conservatory substantially. Or can you close and lock them to keep your home safe but leave a couple of windows open on opposite sides of conservatory? I've been known to use the window sills of my workplace for a bit of growing, maybe that would be an option for you? I would not be happy to leave my dahlias in a coldframe but i am up in scotland, might be okay where you are. You could pull the blinds of your conservatory, white out the windows and i've even been known to put up my parasol to reflect the light back out. You can try a few of these things and record the temps on your thermometer to see what works, then next year you will have a good plan
  • Dirty HarryDirty Harry Posts: 1,048
    edited April 2019
    That's already with the patio door leading into the house open, it can get extremely hot otherwise.

    I'll maybe open a side window too and draw the blinds. I'm in Angus albeit by the coast so there'll be a few frosts yet.

    What would the effects be on the tubers at these higher temperatures?
  • oooftoooft Posts: 191
    That's already with the patio door leading into the house open, it can get extremely hot otherwise.

    I'll maybe open a side window too and draw the blinds. I'm in Angus albeit by the coast so there'll be a few frosts yet.

    What would the effects be on the tubers at these higher temperatures?
    I think when temps get too high they just stop growing. I dont think it kills them, they just kind of chuck it for a bit. They will be stressed. Last year in our hot summer the flowers fell off some of my tomato plants and everything seemed to just stop until temperatures lowered. I'm sure someone more knowledgeable than I will be along with a clearer explanation!
  • NollieNollie Posts: 7,529
    You don’t have window sils you could keep them on Harry? I grew mine on the south facing kitchen window sil and kitchen table, neither gets a lot of light because of deep roof overhangs, but I put them outside on sunny days and this worked. Could this be an option - outside during the day and inside the conservatory during the night?

    This is my first time growing dahlias in pots, my next dumb question is at what point do they outgrow their 3L pots and need potting on, and how do you do that without all the soil falling off the tubers, will there be enough fibrous roots to hold it all together in the move?
    Mountainous Northern Catalunya, Spain. Hot summers, cold winters.
  • Dirty HarryDirty Harry Posts: 1,048
    Window sills aren't an option. Maybe outside during the day and inside at night is a good shout.
  • Dirty HarryDirty Harry Posts: 1,048
    AnniD said:
    @Dirty Harry , have a look here
    https://www.gardenersworld.com/how-to/grow-plants/how-to-grow-dahlias-from-tubers/
    May as well give it a go, nothing to lose after all. Hopefully Crocus will refund or replace.

    50% refund in the end, a massive £3.60. Ignores the delivery price of course.
  • Dirty HarryDirty Harry Posts: 1,048
    I can't be trusted, went out for a hair cut and came back with 4 more tubers from Dobbies.

    They're half price so 4 tubers that are already shooting for £4.

    I'll have to put most of these in pots, I've got about 10 now. Who else does this as opposed to putting them in a border?

    Tallest of them are around 90cm or so, assuming a large pot and staked should be fine?

    How big do the pots need to be for the smaller varieties like Star Wars? I've read a general comment about dahlias in pots saying no smaller than 12" diameter by 12" depth, does that still apply for these smaller ones?
  • LynLyn Posts: 23,190
    The big one needs to go in the garden IMO,  or pot at least 20’ diameter.  
    The small ones can go in pots  about 12” to 15”. 

    I start off new dahlias in pots, then once they’re in the garden they stay there, big pile of mulch over the top in the winter.

    Gardening on the wild, windy west side of Dartmoor. 

  • Dirty HarryDirty Harry Posts: 1,048
    Oh wow as big as that?! Might need to find some large, cheap pots!

    Most of the ones I have are around the 70-90cm mark, these are-

    Bishop of Leicester
    Bishop of Llandaff
    Totally Tangerine
    Night Butterfly x2
    Twyning's After Eight x2
  • Dirty HarryDirty Harry Posts: 1,048
    Have found some large terracotta pots that aren't extortionate. Reckon they'd look ace with dahlias.


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