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Overwintered Dahlias


I overwintered 27 Dahlias grown in individual pots (10")  under my carport. They did not get frostbitten. I have watered the Dahlias a week ago  & they are still under my carport in fairy warm conditions. The stalks have shrivelled up & look dead. I have lifted one plant & it had tubers, about the size of a grape.


How do I know if these plants are alive or dead? If the plants are alive when should they start showing signs of life?


Note! I have since read that you should wait till the first frost & the plant turns black before cutting back & overwintering. These plants did not turn black but were cut back about end September before first frost.



  • ElusiveElusive Posts: 992

    Tubers should be firm and hard. Growth will start showing this month onwards

  • Tropical SamTropical Sam Posts: 1,488

    Have you watered them? Water and heat = growth. I have never left them so long for frosts to Yblacken them and have had them growing for years now.

  • BrummieBenBrummieBen Posts: 460

    patience.. patience.. and more.. I have some lovely giant dahlias, grown in pots in a nice free draining sandy compost I mixed.. I let them dry totally out in september, and then have just started watering 2 weeks back.. There was nothing for ages, several of the tubers on surface were rotten, squidged under my finger.. now today I see shoots.. patience is a virtue!!! The guys I'm talking about make flowers near 10" across, this year I'm making cuttings!!!

  • YviestevieYviestevie Posts: 7,063

    Thanks for asking this question, I was just wondering about it myself.  I started to water my Dahlias about a week ago, just a litlle not soaking them.  Hopefully with this lovely warm weather I might see some shoots soon.

    Hi from Kingswinford in the West Midlands
  • BrummieBenBrummieBen Posts: 460

    oh btw, as it wasn't clear, I DID shift them into frost free about november, the tubers on the top prob got chilled hence the rot, but hopefully the rest were fine.. It's a lesson I shall learn..:P

  • mollismollis Posts: 151

    Mine have just started showing shoots this week. Hopefully yours will show soon too. They were repotted end Feb and placed in a frost free greenhouse. I thought I'd lost them, but they have all come through. image

  • Hostafan1Hostafan1 Posts: 34,734

    I've got over 200 in the polytunnel and last week I'd say there were about 15 showing growth, this week, 2 or ever 3 times that. Too busy to check them all but they're starting .

  • Hostafan1Hostafan1 Posts: 34,734

    BILLYC, why did you cut them in Sept? Mine were still in flower in November.

  • BILLYCBILLYC Posts: 70

    Thanks to everyone who responded to this post. All very helpful. Today I uprooted one Dahlia & took it to a professional gardener at my local garden centre. He examined the tubers & pronounced all is well, tubers are healthy. Advised me to cut down last years old growth to ground level & cover with compost & feed & water. Hopefully plants will grow soon. 

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