HI All,
weeding the front garden i find that i have couch grass which means its not going to be long before it hits the back garden. A neighbour tells me that they have it in there pack garden and attack it with a blow torch once a month.
Well when i put the raised beds in the back garden there going to be about 2ft deep so my thinking is that i lay weed membrane down the beds (in fact put the beds over a sheet of membrane so its got a good foot each way the other side of the bed). So do you think this will stop the couch grass and allow me to plant stuff? I am thinking that as long as i dont plant spuds (not planning to anyway) then i should be ok as the beds are deep enough.
Was going to build the beds up with layers of paper (collected from local newpaper), then a layer of spent hops, then soil improver with a couple of bags of Vermiculite mixed in to help with moisture retention and to improve the soil texture.
I am hoping by adding the membrane to the bottom it will stop the couch grass taking hold in the beds.
Cam
Would a thick layer of cardboard at the bottom help?
Can't see it hurting but is that instead of the membrane?
I think you are giving yourself a bit more work than you need to, couch grass normally goes to a depth of 6" so i think it is pointless taking your raised beds down 2 feet and putting membrane below the depth that couch grass roots spread.
My option would be to turn over the area where each bed is going to go clearing it of any roots and put the membrane round the walls of the trench so the grass can not get in from the sides. The dig a narrow trench around the outside of the trench about 8" deep to stop any grass from reaching the trench.
If you've got couch grass then try and keep it away from rotting wood or layers of paper - the roots love penetrating this stuff and its 5x as hard to get it out.
This means keeping any wooden raised beds clear of the soil if you can - a line of bricks as a base is better, possibly the best base is old UPVC door frames from skips - cut up so they become straight 80x80mm beams that slide under and support the wood.
You can try putting plastic sheet between the couch and the wood but in my experience it just makes the wood rot faster.
Couch will pierce anything thinner than dampproof membrane and will pierce even that when the sun has got to it for a while - then it runs riot along the plastic.
It came through the weedblock I put at the bottom of my 18 inch raised beds and grew up among the strawberries. xxJeannine
I don't know what you've got round the side of the house but is there any way you can create a buffer zone where you can blast any couch with weedkiller or dig it up? Meanwhile, if you mow the front garden, that'll kill it over a season.