Have today eked out the last remaining bit of space to make a bed on my half-plot. It has previously been part of a blackcurrant bed and part grass path. Totally infiltrated with couch, scutch or whatever else you call it ( I call it many things ) Any road up, after spraying with glycosphate and waiting for it to show signs of some effect, I have dug out as much as humanly possible and put it into rubble sacks. What I really need to know is how long should I leave it alone before I can reasonably expect it to have gone to the great weedpile in the sky? Are we talking months or years? Wouldn't have been a problem before, but now space is at a premium and I aspire to an aesthetically pleasing plot, also, I wouldn't mind a chance at 'most improved plot' this year!
Since you've already killed it, it could have gone onto the compost heap rather than rubble sacks, where it would compost rather than fester, as weeds tend to do when enclosed in plastic. On the other hand, there is the risk that it has not all been killed, especially if you have only recently applied the weedkiller. I find couch is quite late to emerge, and for glyphosate to work well it needs to work through the emerged foliage. Also, this early in the season it is slower to work; it is slow-acting in any case. I've successfully eliminated couch from a plot in the past entirely by digging it out only. I made a heap of everything I dug out and covered it with a tarpaulin for two years, after which it completely rotted. It may not have needed that long to decompose, though, that just happened to be how long I left it for. You can never eliminate it in the first year, but anything that reappears can be forked out. This is assuming that the plot is bare, of course. If the blackcurrants are still there, then the couch runners get intertwined, and that's a pain.
Thanks Felix, pretty much as I suspected. Didn't want to put it in the compost just in case. I have retained one blackcurrant just so I can have a crop this year until my new bush is up and running (that is in a different part of the plot, hopefully couch-free). Will just keep digging out as usual and will probably spray the edges if necessary.
I have a couch grass question: At the allotments, couch is endemic in the grass paths separating plot from plot, so eliminating it from an induvidial plot is a hopeless task. I know when the task is essentially one of limitation! However, is there any advantage to be gained from a physical separation between the plot and the surrounding paths? for example lawn edging If so, how deep do couch roots go, when running across the ground? There is no point in doing the work if the couch just ducks underneath and continues to spread. I'll stick to pulling it up/digging it out where neccesary.
Nothing is foolproof to a sufficiently talented fool.
) Any road up, after spraying with glycosphate and waiting for it to show signs of some effect, I have dug out as much as humanly possible and put it into rubble sacks. What I really need to know is how long should I leave it alone before I can reasonably expect it to have gone to the great weedpile in the sky? Are we talking months or years? 
