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Preparing a new raised bed on turf / lawn

WildFlower_UKWildFlower_UK Posts: 236
in Fruit & veg
Sorry if this has been answered elsewhere but I couldn't find anything by searching.

We will be installing a raised bed made up of old scaffold boards. We will be placing the frame on our lawn in a sunny location. But I'm reading conflicting advice how to best prepare the ground. I intend to stake the boards into place at the corners with concrete, and fill with a compost/topsoil/manure mix. The sides will one board high (so around 12 inches) - the shape is L-shape and will be roughly 2mx2m with a missing 1/4. Do I:

Cut out and remove the turf completely? We have the usual dandelion and aggressive grass (not sure but maybe couch grass) in some patches.

Cut out and turn over the turf? I heard this means less soil mix is needed to fill the space, and can also help with drainage.

Put cardboard down between the cleared/turned over turf and new soil mix? I know it will break down eventually but not sure if I'm too late in the lead up to do it.

Not sure which is the best combination. Happy to remove the turf but not sure how to turn it into compost/soil? 

I want to start using the beds this year for growing veg. Although we will be rotating crops year to year, this year I  plan to grow some dwarf French beans, basil, beetroot and courgette plants in the new raised bed (I have other planters, pots, containers for other plants).

Thanks in advance :)
"If you have a garden and a library, you have everything you need"

Posts

  • clare_graceclare_grace Posts: 27
    Hi, last year I did the Cut out and turn over the turf method. It worked a treat. I still needed to add lots more soil on top of the turned over turf so having the turf there really cut down on the extra soil needed. Within a few months the turf had broken down and there were lots of worms which indicated all was well. No extra weeds noticed. Most importantly lots of veg produced ( although I planted the wrong veg in the wrong place and won’t make that mistake this year. Lesson to me was to grow what you want to eat and don’t plant bulky veg next to dainty veg). Only think to add is that if you have put down any grass treatments over the last few months I wouldn’t use this method. One othe huge bonus of doing this is it is very quick to do and you don’t end up with a lot of turf to get rid of. Any extra turf I saved and put in The bottom of my sacs for growing potatoes. Hope it all works out well.
  • JennyJJennyJ Posts: 10,576
    When you're lifting and turning over the turf, take out as many of the dandelion roots as you can because they'll most likely regrow even if buried (I've had them growing inside the compost bi when I accidentally put some in there instead of in the council green bin). Same for any other tap-rooted weeds that you come across.
    Doncaster, South Yorkshire. Soil type: sandy, well-drained
  • WilderbeastWilderbeast Posts: 1,415
    Personally if your putting 12inch depth of soil mix on top I'd not bother digging the base up at all. Your unlikely to ever see the soil down there for many years and your just going to fluff up the soil which will just sink again meaning that next year you will need even more soil/compost to top them up (the new soil will sink anyway).

    Cardboard laid under that depth of soil will break down nicely and will certainly not stop roots travelling through it. If you do have couch grass then you won't remove to unless you remove every single scrap of root, it's pretty unlikely much would make to the surface of it's undisturbed and what did would weed out easily. 

    I've just reread this and it sounds like I'm a proper "no it all" I don't, you'll have great success whichever way go so long as you get good quality soil to fill the bed. Hope it all goes well 
  • Blue OnionBlue Onion Posts: 2,995
    I did the cardboard covered in 8 inches of soil, no issues with weeds growing up though.  Cardboard has long rotted away, and now I have issues with couch grass coming up from under the sides.  No matter what you do to the soil under, consider some sort of non-grass border around the edges.  That is my biggest regret.  
    Utah, USA.
  • WildFlower_UKWildFlower_UK Posts: 236
    clare_grace said:
    Only think to add is that if you have put down any grass treatments over the last few months I wouldn’t use this method. 
    Thanks so much! Glad to hear it worked really well for you! We haven't used any treatments on that part of the garden so all good there.
    JennyJ said:
    When you're lifting and turning over the turf, take out as many of the dandelion roots as you can because they'll most likely regrow even if buried (I've had them growing inside the compost bi when I accidentally put some in there instead of in the council green bin). Same for any other tap-rooted weeds that you come across.
    This is great! It's not such a huge area that I can't do some serious de-weeding before starting on turning the turf over.
    Wilderbeast said:
    I've just reread this and it sounds like I'm a proper "no it all" I don't, you'll have great success whichever way go so long as you get good quality soil to fill the bed. Hope it all goes well 
    Eurgh couch grass is just the worst! Thankfully there's not much where the new raised bed will go, but quite close to it. Thanks so much for your comments; it's very much appreciated!
    Blue Onion said:
    No matter what you do to the soil under, consider some sort of non-grass border around the edges.  That is my biggest regret.  
    This is something that I've thought of - need to find a way to make the area look smart if I do this, as space around the new raised bed is tight and will get close to other borders/beds. Thank you :smile:
    "If you have a garden and a library, you have everything you need"
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