dahlia tubers in ground through winter question.

Hi I planted some dahlias last year they grew n flowered like there supposed to n so on but I never dug the tubers up for the winter two were in pots and one in the ground what be the cut off month if they havnt started to grow by  that would mean they had died?



  • Ok,thanks very much for the advice.

  • ladygardener2ladygardener2 Posts: 340

    Where I live, we're into May before outside tubers left in the ground over the winter start to sprout. Depends where you live among lots of other things as Verdun says.Despite it being very wet, I moved a couple of mine that I'd left in the ground as I'm making a new dahlia bed. The tubers were plump and fine, no sign of rot at all thankfully.

  • I always play safe and dig the tubers up at the end of the flowering season just after the first frosts have blackened the foliage. I clean/trim the tubers and then store them wrapped in newspaper in a cool, dry and frost-free place over winter. Rot can be prevented by dusting them with sulphur powder.  Using this method I recover 90% plus of the tubers ready for potting up now or planting out in late April. 

  • Where can you buy sulphur powder Malcolm? 


  • Rosie31Rosie31 Posts: 483

    Hi Sam

    As Verdun says, it's tricky!  Why not keep checking back with this forum to see how others' dahlias are doing (and if you can tell us where you are and what sort of soil you have, even better).  Then if everyone here - especially people who live near you - is saying their plants are up and growing away, and you still have nothing but bare soil....maybe that's the time to write the obituary!


  • Angela at 27 wrote (see)

    Where can you buy sulphur powder Malcolm? 

    Hi Angela - I bought it at a local garden centre. It comes in a plastic bottle with a nozzle that allows you to blow the yellow sulphur powder onto the surface of and into small spaces between the tubers and on all cut surfaces.  (It can also be used as a soil acidifier - useful for growing azeleas/rhododendrons on a neutral Ph soil).


  • AtillaAtilla Posts: 1,493

    The problems with Dahlia staying in situ over winter, assuming great drainage and that they have not rotted, is that they take an age to regrow as the soil is too cold until May. Same with Canna, which are hardier. You just get a poor and late display that is often cut down with late frosts. You could try covering the bed with a plastic sheet to heat the ground that few more degree.

  • Busy-LizzieBusy-Lizzie Posts: 12,095

    I don't dig my dahlias up and most of them survive, but every canna I've left in the ground has died. So I'm surprised Blairs says Cannas are hardier.The dahlias in the ground have leaves by May, but that may be because in Dordogne the warm weather starts earlier, but the winters are usually colder than in the UK.

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