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I leave my dahlias in the ground and mulch heavily over winter and have had good flowering success this summer, however, we are all informed to cut down the dahlias after the first frosts when the leaves and stems blacken. My concern is this - I live in mid Norfolk and our autumn and winters are very mild. We have had 2 frosts with no effect on my dahlias and chances are we may not get a heavy frost(s) this side of Christmas. if this is the case, when is the best time to cut them back if the leaves/stems don't blacken in readiness for winter mulching? Thanks for your help.


  • JennyJJennyJ Posts: 10,079
    The mulch is to protect the crowns from frost, so you can delay mulching if you aren't expecting to get hard frosts yet.  My dahlias seem unaffected by the couple of frosty mornings we've had and still have flowers, so I'm leaving them alone for now. I'll cut them down and mulch when all the flowers have gone over or when they get blackened by a harder frost, whichever happens first.
    Doncaster, South Yorkshire. Soil type: sandy, well-drained
  • punkdocpunkdoc Posts: 14,606
    There is no need to wait for the stems to blacken, before cutting down / lifting.
    How can you lie there and think of England
    When you don't even know who's in the team

    S.Yorkshire/Derbyshire border
  • Hostafan1Hostafan1 Posts: 34,735
    If, repeat, IF, you expect very little frost, and your soil is free draining , you may, repeat MAY, not have to lift them. Your plants though, your gamble.
    I couldn't even think of it here in very wet Devon.
  • I left mine after the first frosts as it did not affect them but then a much harder frost has blakened them now. I have said this on another thread, but  I tried leaving mine in the ground & they did survive but the slugs & snails eat off all the emerging shoots ! So I have reverted to lifting them again.
    AB Still learning

  • Hostafan1Hostafan1 Posts: 34,735
    I looked after a garden in W. Sussex and there were dahlias  there which were never lifted in the 15 years I looked after it. The only time they were dug up was when the house was being sold and the owner wanted to take a chunk to her new garden, and to give me some too.
  • LynLyn Posts: 23,064
    I never lift mine, they are blackened now after the frosts last week, cut down and they will be mulched a bit later on.
    If they haven’t blackened, leave them until they are, makes a bit of greenery in the garden for as long as possible. 
    Gardening on the wild, windy west side of Dartmoor. 

  • I leave my dahlias in the front garden in the ground and protect them with straw covered with fleece. Front garden is a lot drier so they do ok. They even survived last winter. Back garden is wetter so i lift them and store in the shed. Those in pots get cut down and put in the greenhouse and covered with bubble wrap. I think it is more damp that will do for a dahlia so if you are dry then leave in the ground. Less hassle!
    Gardening. The cause of, and solution to, all of my problems.
  • Just checked my overwintering Dahlias and they have a white 'fluff' on the stems. Anybody know what this is?
    Gardening. The cause of, and solution to, all of my problems.
  • DovefromaboveDovefromabove Posts: 86,925
    edited December 2018
    watlingg said:
    ... - I live in mid Norfolk and our autumn and winters are very mild. ...
    Don't count on it ... I can remember temperatures around -17C  in the mid 80s ... not that long ago really.   When the east wind whips across ... there's nothing to slow it down between here and the Urals :o

    Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.

  • Nanny BeachNanny Beach Posts: 8,669
    Someone pinched my thread, I live in East Sussex, near South Downs, 10 minutes from the sea, wasnt sure if I should take them up, I did a few years back they didnt survive.  I have planted a lot this year, we havent had a frost, some top growth had gone black.  I also have garden news they say leave them in as long as possible to ftten up the tubers for next year.   I went and knocked on the door of a chap who lives a mile away, having gone past his huse for the past 7 years, admired his dahlias, some are still flowering now.  he said hes been in the house 75 years, not sure how old he is, lovelly chap, invited me in.He said he has never removed them they have been in 5-7 years, he doesnt mulch them, just cuts them down to about 6 inches.  We had frost forcast one night last week, so I mulched all of mine with home made compost, and put a wicker, (plastic lined) hanging basket over the top of each one, and am keeping my fingers crossed!
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