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acanthus mollis - does it spread?

NormandyLizNormandyLiz Posts: 788
in Plants
I have some Acanthus mollis plants I germinated from seed. The main location I have for them they can do what they want to a certain extent but I am also thinking about another location for one. 

The question is - do they spread? I'm getting conflicing information online. GW says they don't, other sites such as https://www.gardeningknowhow.com/ornamental/foliage/bears-breeches/grow-bears-breeches-plant.htm say they do? Given how difficult/impossible they can be to get rid of if you do want to move it, I really want to make sure I don't put it in a place it might take over unasked. Plus if they do spread I'll be more restrained in how many I put in the 'go for it' area (i.e. 1 instead of 3)


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  • bédébédé Posts: 3,095
    edited February 2023
    Acanthus mollis  grow easily from seed.  I have some from seed I collected in what looked like wild at Lands End, Cornwall.  Growing in a stone wall and wild strip below, on a steep slope, South-facing and facing the sea.

    They also grow easilly from root cuttings.  I have moved plants, and when I do I find that I get regrowth from the broken-off roots in the original position.  IN my case, the reason for moving was encroaching shade, so I just leave the new plant to do its best.  I imagine that with a couple of hoes they would be gone.

    Seedlings come up in my compost heap unbidden.  So if you let the seed ripen and fall, you might have a problem.  It is tempting to leave the very decorative seed heads as longas possible.

    I also grow Acanthus ?spinossimus and Acanthus ?hungaricus that perform similarly.


     location: Surrey Hills, England, ex-woodland acidic sand.
    "Have nothing in your garden that you don't know to be useful, or believe to be beautiful."
  • NormandyLizNormandyLiz Posts: 788
    Sorry, I don't know if I phrased the question badly. It's not about the germination, that's done and the plants are waiting for spring to go out. It's whether once established the plants will spead unbidden. According to that link I put 'he plant will spread via underground runners

    According to that link I put, 'The plant will spread via underground runners, and in areas with yearlong warmth similar to its native Mediterranean climate, it may very well take over your garden', which is a daunting prospect for a plant whose roots you can't eradicate!
  • GrannybeeGrannybee Posts: 332
    We have a big one, it has got bigger over the last 25 years but hasn't taken over. I didn't know they spread! We have very poor soil -dry,  stony and chalky so that may have prevented it from getting too big. Are there any in gardens near you? If you have good soil, I suppose they could take over!
  • JennyJJennyJ Posts: 10,576
    The plain green one does, for me, but so far not as vigorously as A. spinosus. I have a couple of variegated ones (Whitewater) that are a bit puny so far.
    Doncaster, South Yorkshire. Soil type: sandy, well-drained
  • GardenerSuzeGardenerSuze Posts: 5,692
    edited February 2023
    I grow Hollard's Gold it has to be kept in check, enjoys coming through the roots of plants nearby.. I think some will describe it as invasive. Certainly difficult to get rid of  completlely if that is your plan, will reappear year on year as roots are deep. Having said that I still love it and accept it has to be continuously tamed. Some flower better than others I have tried to dry the flowers but no success.
    I have worked as a Gardener for 24 years. My latest garden is a new build garden on heavy clay.
  • nutcutletnutcutlet Posts: 27,445
    they spread by root and seed, probably not one for a small garden but great if you have the space


    In the sticks near Peterborough
  • bédébédé Posts: 3,095
    edited February 2023
    I mentioned germination and root cuttings for completeness and for the benefit of others.  The reference to Lands End links to your climate, and the wildness refers to its natural distribution.  It is not invasive in my garden.  There are no sign of underground suckers.
     location: Surrey Hills, England, ex-woodland acidic sand.
    "Have nothing in your garden that you don't know to be useful, or believe to be beautiful."
  • FairygirlFairygirl Posts: 55,117
    You said you'd already germinated seed @NormandyLiz, so no need to worry - it was perfectly clear  :)

    They do spread by runners underground, so in some soils they might get a bit rampant. I've not found that, although I've not grown it for a very long time, but our soil is heavier and wetter, so that may help.  Many plants are the same.
    It might come down to experimenting with your conditions.
    I don't know if a root barrier would help?
    It's a place where beautiful isn't enough of a word....



    I live in west central Scotland - not where that photo is...
  • NormandyLizNormandyLiz Posts: 788
    Thanks for everyone's replies so far. I'm glad I checked/asked, having read several 'doesn't spread' notes on a couple of places including GW, I'm not sure what made me look further but I'm glad I did.

    Fairygirl said:

    It might come down to experimenting with your conditions.
    I don't know if a root barrier would help?
    With most other plants I'd be happy to experiment but with one you can't easily eradicate if it is in the wrong place, I'd rather take precautions first. How deep do you think a root barrier would need to be? I'm assuming the roots aren't that wide so large plant pot diametre would be enough, but how deep?

    Then I just read this  :lol:

    https://www.burncoose.co.uk/site/content.cfm?ref=Acanthus+-+Care+Guide

    and started to wonder if I'm mad to even want one, never mind several!
  • bédébédé Posts: 3,095
    edited February 2023
    Burncoose Nurseries are in mild, perhaps Seine Maritime-like, Cornwall.  What they print is not my experience.  Roots could be 0.5m deep and 0.5m spead and up to 1.5cm wide.

    What do the locals say?

    Go on, risk it.
     location: Surrey Hills, England, ex-woodland acidic sand.
    "Have nothing in your garden that you don't know to be useful, or believe to be beautiful."
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