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Do I need to use a liner on a raised bed?

Hi again - some of you may remember my recent posts about removing lots of invasive reeds by my pond/stream.  Got lots of excellent planting ideas and got in touch with a site that specialises in bog plants and plants that don't mind wet soil and shade.  Am going with various types of Primula and some Astilbe.

I have now realised that this particular 9' patch is TOO wet, we had one day of rain and it's just terrible, so, I am going to put a low raised bed in there, our carpenter/builder used some wood on our pharmacy that is guaranteed for 30 years so am thinking that's my best bet BUT if I put a liner in won't I then be turning that area into a normal planting zone and the damp loving plants won't like it?  Am I making any sense here?

The benefit of the raised bed is that the grass won't get a foothold either.  I was going to go for a lowish one - looked online to get ideas ... which do you prefer?  Knee height or the really low one?
I've just spent two days solid digging out silt the full length of that stream with a trowel so I wouldn't damage the liner - got bitten to death :#

mid height

Or the log look - I like this but won't be able to get it with the long guarantee that the other material has, think this has a 15 year one.



  • FairygirlFairygirl west central ScotlandPosts: 49,135
    Yes - you need a liner. It protects the wood. It also retains moisture, so it's fine for the damp/bog loving plants. They'll draw up the moisture from below.
    I've done it many times, and it's good for creating wetter areas within a drier bed too. 

    Perhaps you'd be better looking at stone/brick for the edging though. I don't see the point of making it high in that site - it just means more filling.  :)
    It's a place where beautiful isn't enough of a word....

  • Yes,as fairy says
  • FairygirlFairygirl west central ScotlandPosts: 49,135
    @Nanny Beach - I see you've sent me a PM - unfortunately I can't see them properly [been like that for months] but I did see the pop up which appeared and was lucky enough to read it in time.
    Thank you for the support.
    It's a place where beautiful isn't enough of a word....

  • ren.bren.b Posts: 161
    We've added a lot more rocks to the edge of the stream there but it is literally sodden, the stream is nearly the same height as the ground there so keeps flooding over, I've dug out all the silt - right down to the pond liner. thanks as always for your advice. <3
  • Fairy tick!!
  • FairygirlFairygirl west central ScotlandPosts: 49,135
    Fairy tick!!

    @ren.b - if the area floods, you may need to take a different approach. Bog plants, but ones which can cope with a bit of drought too. 
    I can recommend Spartina - a grass which is suited to exactly those conditions.  :)
    It's a place where beautiful isn't enough of a word....

  • LoxleyLoxley NottinghamPosts: 4,976
    Just a personal observation, but those raised beds look more appropriate to a vegetable plot than what is currently a nice natural area by the pond. To raise the soil level I would simply make a mound of soil (incorporating grit), to about 30-45cm ht in the middle, and plant it up. You could lay large stones around the edge if you have them, which could increase the height further. 
  • LoxleyLoxley NottinghamPosts: 4,976
    edited September 2021
    I would remove the grass from the whole area, up to the path, to minimise having to 'edge' the bed. 

  • FairygirlFairygirl west central ScotlandPosts: 49,135
    I'd agree @Loxley - I suggested stone or brick too. I don't think timber is the right material for that kind of area at all. Planting can be tailored to spill over edges a bit as well. 
    Increasing the area would certainly help. Easier to blend all the areas in together, and more plants means less 'wet'.   :)
    It's a place where beautiful isn't enough of a word....

  • ren.bren.b Posts: 161
    Hi guys, I've already got two stone raised beds, see pic 1, and haven't got the time, energy or money to get a ton of stone delivered and find someone to cut it and build (only just managed to get rid of the last dregs after 8 years).  I don't know if I've got the time to look after an area of plants that big (the area you suggested Loxely, it would need constant weeding etc, the grass always manages to regrow, it does it in my hosta area despite lots of cobbles.  Might put some edging at the back of them.

    I do agree with you about the timber - but I think that we have found the cause of that particular patch being wetter than anywhere else on that side - widening the stream walls and strategically rearranging the rocks to create tiny dams further up, clearing it of 8 years worth of silt will also make a difference.

    Not sure what to do right now to be honest, I'm knackered after digging up a border, we found rocks underneath about 2' big ... building rubble!!  If they've dumped over there too it will all have to be dug out.  I wonder if I can get something else to use as a planter that isn't made of wood or stone?  I just wanted something there instead of those awful reeds so when I got those out that's when I thought about a planter.  If THEY grew so well there, do I need to raise it at all if I sort out what's causing the soil to be so damp in the first place?

    The reeds seemed to be 'too happy' here ... got really messy and difficult to get to the old growth.

    Do you think the primula will be as happy in that area as the hosta obviously are?  Without my having to raise it?
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