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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?

Hi sam

There is no " cut off point" as such........last year one or two dahlias were,very late in showing growth. This year some are shooting and others aren't.

However, I assume your dahlias in pots were,left outside too.  It's a difficult winter to say if dahlias will survive because of the non stop rain.  I'm in a very mild area where pelargoniums and gazanias are still,flowering but dahlias with their tubers buried may have rotted this year.  I dont know yet.   So, I would say mid April we should see dahlias shooting.  I left begonia corms outside in pots and will check on those later.

Although its been a wet winter it hasn't been cold so maybe these things will be fine.

(just checked my begonia corms and they are solid and not rotten so hopefully dahlias.....both yours and mine....will be ok too)

Ok,thanks very much for the advice.

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.

Malcolm Harrison

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? 



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!


Malcolm Harrison
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).



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.

Yes think blairs is absolutely right. 

Both dahlias and cannas benefit hugely from an early start. Because its so mild here mine do stay inmthe ground and shoot early.  However, I also plant in large pots under polythene, GH or conservatory for planting out in mid spring.  They flower so much earlier then.


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.


Last 'spring' I dug up a couple of dahlia tubers that I found were in the way when planting new shrubs and placed them, half buried, in trays of MPC in the cold GH.  They produced shoots much earlier than those I had lifted in the Autumn and kept in dry sandy peat, as well as before those left in the ground.  They flowered a good month before any other dahlias in my garden.  I intend to do the same to any I find are  'in the way' this year.

Busy Bee2

When I first grew dahlias from seed I didn't know they were anything but annuals, so was surprised and delighted when they re-appeared the following year, and the next two years after that.  But when we had a cold winter they perished.  They were 'spoiled' by the fact that they live in well drained soil in raised beds under bark chippings.  I seem to remember that they didn't show signs of life for some time in the spring, so I would wait if I were you.  I bought some 'stocking filler' dahlias last year for 50p at the GC, to fill a bare spot, and it didn't occur to me to take them up, so I am watching with interest to see whether in this year's mild winter they have survived.  No signs yet, but it may be a bit early. 


in my last garden with sandy Hants soil,with little rainfall, I left my dahlias in the ground. However now in north Devon on heavy clay with TONS of rain, I lift them, all 200 of them . OH despairs when he sees them start to carpet the garage floor, tee hee.

hello i plant 4 plate sized dalhias from the range back in early april and there is no sign of any growth should i leave it for another month before i check the tuber to see if its rotted or not 



stephen moulder wrote (see)

hello i plant 4 plate sized dalhias from the range back in early april and there is no sign of any growth should i leave it for another month before i check the tuber to see if its rotted or not 


Where did you plant them? I need to start mine off in the greenhouse in pots - most are not a good few feet tall now. I would never start them directly outside in the borders, as they take a long time for the right temperatures to develop for them to grow well then flower.

You can tell when they have rotted as the brown rhizomes will turn to mush or be hollow.

hi I planted some directly in the ground and few in tray on windowsil. The one in the ground are just peering above the ground. Howeve the on in a tray no sign. Should I have not watered them.

Hi wanna be Gardner, 

I would take them out of that tray and pot up into small pots.  Check the tubers first.  If they are firm and healthy or even a little dried (cos they may be in that tray) up they should respond well 



My dahlias have just poked up out of the ground in the last week - two inches above ground now.  I'm in south wales, on clay soil, and I spread a thick (6 inch) layer of mulch (leaf mould) on the bed before winter.

Now I can see where they all are, I can start putting the other plants in around them!



I dug up my dahlias and stored then in a tray in the shed to dry out. All sound, so cleaned them up and re potted them early this month. Only one shows signs of growing so far and with the soaking they have had will have to be patient I think. Warmer weather forecast for Herefordshire next week.