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Dahlias in Devon - in the ground or not?

After 27 years of gardening I have finally succumbed and bought a couple of dahlias, because they were half price, neglected in a corner of the plants sales area at Mole Valley Farmers.They weren't labelled, other than 'Orange Patio Dahlia'.

I only bought them three weeks ago so have left them in their pots for now, but I want them in a border long-term. Should I put them in the ground now and leave them under a thick mulch over winter, or is that not safe even down here in Devon? I have to say it's the first time I've had such lovely colour in the garden at this time of year - they are still producing new flowers - so I've kind of fallen under their spell a little. I predict more dahlias in the garden next year!

As a Dahlia virgin, any other advice would be very welcome.



  • Hostafan1Hostafan1 Posts: 33,683

    I'm in Devon to and I lift mine. Not because of cold,but the rain. 

    I'm on heavy clay soil and it can become waterlogged, instant death by mush to dahlias. If you have sandy, free draining soil, you should, I repeat " should" be ok. I  used to leave mine in the ground when I lived in Hampshire, but I'd not dare here.

  • I live in Devon and I left them in the ground last year.

    I cut them down after the first frost , mulched the bed with well rotted leaf mouldy and then covered with garden fleece . They were fine and even stronger in growth than previous years when I have lifted.

    they are in a well draining bed but I do live on the edge of Dartmoor so the weather can be quite severe.

  • Thanks Hosta and Chrissy. I'm ashamed to say I can't really identify my soil type. It is SO bloody stony that there's precious little in the way of soil particles to pick up and squish. Perhaps I'll venture outside in a bit and have another study of it. Although I've been at this house for seven years I'm sort of starting from scratch again this year. I planned and planted in my first year, lost tons of babies due to the two back-to-back severe winters in my first two years here, then went through a messy divorce and the garden was completely and utterly neglected for almost three years. The soil in one big border was like concrete when I started over again this spring. I think I'll keep my new babies in the greenhouse this year and worry about them again next autumn, when I've had more time to reacquaint myself with my plot.

    I think I've spent more on compost and manure this year than I did in the previous 26 years of gardening image

    Last edited: 28 October 2016 09:34:42

  • Hostafan1Hostafan1 Posts: 33,683

    2 days after digging mine up 2 years ago , the holes I'd left behind had filled with water.image

    I'm tempted to leave one my Imperialis in the ground as the tubers are almost 1m across and the plants are over 2m tall.

  • Wow Hosta! I just googled them - they are gorgeous! Tubers 1m across - no wonder you don't want to lift them. It never ceases to amaze me how much growth plants can put on in a season.

  • Hostafan1Hostafan1 Posts: 33,683

    thankthecat. I collected the seed on a mountainside in Tamil Nadu in Southern India.

    Check me out!!!!!

  • Once we get a frost, do you think I should just cut off top growth and leave the tubers in the pots in the greenhouse, or remove them and let them dry out?

  • YviestevieYviestevie Posts: 6,957

    I live in the Midlands and always leave my Dahlias in the ground.  I may lose the odd one, usually to slugs and snails, but most come through the the winter OK.  I'll just accept the loss if we have a really bad winter as I can't be bothered with all the faff of digging  them up and storing them.  My soil is neutral and a good consistency, no clay but not too sandy.

    Hi from Kingswinford in the West Midlands
  • pr1mr0sepr1mr0se Posts: 1,178

    I'm in Devon, too, and have lifted my dahlias today to be stored overwinter.  In the past, in even warmer Somerset, I have gone down the "leave & mulch" route, but have found that they can still be vulnerable to the cold and, as Hosta has  said, the wet of winter.

    Once the tubers have drained and dried, I shall wrap them in newspaper and store until next spring.  It works for me, and the plants don't become too large for their space, which they can otherwise do. It is easy to split the tubers to make extra plants, too.

    I hated cutting out the flowers when they were still giving me so much colour in the garden, but some of the leaves had been blackened by the bit of early frost we had recently.

    On the plus side, I now have two vases of colour indoors!

  • Thanks Violet - what do you mean by 'drained' though? Do I just dry them out on a rack or something? As they are currently in pots I wondered if they would keep in there overwinter, if I don't water them?

    Last edited: 28 October 2016 18:32:44

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