Creeping Thistle Control

Posts

• GardenerSuze Posts: 5,692

  September 2023

  @The sustainablegardener This is a really difficult weed. I worked in a garden where we never got it under control.
  The long roots go under paths and out the other side. That is the problem any chemical control won't find it's way to the roots and it will simply regrow.
  Most gardeners will have at least one weed that is annoying surely that is part of gardening complaining about a pernicious weed?
  I garden organically and sustaining both flora and fauna is important, I would leave the chemicals at the GC personally. 
  
  

  I have worked as a Gardener for 24 years. My latest garden is a new build garden on heavy clay.

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• Liriodendron Posts: 8,328

  September 2023

  I no longer use weedkillers, and have creeping thistle which grows under the garden wall from the field next door.  However, there's not so much of it that I can't give it a headache by digging up every bit I see...
  
  However.  If you've got a big area with nothing growing in it except creeping thistle, you can most definitely kill it with glyphosate - BUT you have to apply it a the right stage of growth.  You have to sit on your hands until the thistle is flowering, and then spray it with glyphosate at the maximum recommended strength according to the packet instructions.  This works for all fast-growing perennial weeds, like rosebay willowherb and even japanese knotweed, though knotweed needs treatment in several successive Septembers.
  
  As @GardenerSuze says, weedkiller often doesn't find its way to the roots.  This is because in spring and summer the plant is growing really fast, from a lot of thick roots which are providing it with food.  The plant juices are flowing upwards.  Once the plant has finished growing and started flowering, it's beginning to prepare to die down to its roots for the winter, and the plant juices (and weedkiller) are then absorbed back into the roots.  Timing is the key - too late, and the seeds will be blowing all over your garden...
  
  Good luck.

  Since 2019 I've lived in east Clare, in the west of Ireland.

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• Fairygirl Posts: 55,117

  September 2023

  Interesting. It's everywhere around here, verges, open ground etc, but it's never been a problem in gardens that I've had, and I've had two in the same vicinity. I've really never seen it in other gardens I go past either. 
  I think @Liriodendron's advice is sound though. It's often about timing for using any weedkiller, but if you also take off any flowering heads, that will at least prevent too much seeding around. 
  All the new weedkillers don't have glyphosate, so I expect it depends on where and when you buy it. I last bought weedkiller about 18 months ago [at least]  and it was all the new stuff that was available. 

  It's a place where beautiful isn't enough of a word....
  
  
  
  I live in west central Scotland - not where that photo is...

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