Drop some white vinegar into the middle of the couch grass. Get some newspapers, enough to cover the couch grass, pour over some more vinegar and then lots of water leave for a week to 10 days, keeping wet and that will kill off the couch grass - scale up or down depending on size of affected area. Vinegar only has a mild affect on the soil pH, so no affects on your wanted plants.

You have my sympathy Gattina - I have a fully planted bed in a client's garden which has a constant problem with this. The plants are mostly ground cover spreaders, so difficult to dig it all up and try to extract roots. Currently I'm trying glyphosate sprayed on, but its difficult because its growing in amongst the plants, so I have to use a sheet of polythene or something to cover the main body of plants I don't want killed.
RHS has similar advice - google treatment for couch grass and select the RHS page - gives info on best times to treat, etc.

Is fluazifop-p-butyl available in the UK? It will kill grasses in the middle of a wide variety of broadleaf plants.

It would seem its licensed for use amongst hop crops here, but nothing on line suggests its available to ordinary gardeners, Tugbrethil. I'd like to get hold of some of that myself, never heard of it before...

The only brand available to home gardeners here in the States is Ortho Grass-B-Gon.

Do you think it might be available in Canada, or British Columbia, as well Tugbrethil? Cos if it is, I'll ask my relatives to bring me some next time they visit...

I was thinking that, Bamboo, but you have to be awfully careful what you carry in your luggage on planes these days - if I remember rightly, weedkiller (of any sort) is specifically mentioned as a no-no. I've been trawling European sites in general this morning since reading your message, Tugbrethil, to see if the parent company does anything similar but maybe under a different brand name, and have drawn a total blank. Strange, isn't it?

Not really, Gattina - the EEC and UK often have different rules regarding chemicals - some medicinal drugs are permissible in the States but not here, and the other way around, and the same applies to pesticides and herbicides. But you may have a point with bringing a bottle of pesticide into another country, specially these days.

I believe the reasoning behind it is that use of certain weedkillers can form part of the production of explosives. I see your point about the different laws in various countries.
I just found it strange because a few (well, quite a few, now) years ago, I know that such a product WAS available in the UK. Could be one of these blessed EU rulings that no-one but the Brits. bothers to observe.