step back

[charles]

 I suggest you cover it exactly as you are guessing, but I would not plant asparagus until March 2013 because there is now only half a season until winter, not long enough to exhaust bindweed roots in particular. Spread a good couple of inches of any half- or well-rotted organic matter on top of the mown weeds before covering. Keep the light excluding cover on until about next June, then remove it and clear any visible weed roots (with a trowel probably) and  then plant some leeks or kale or whatever for next autumn and winter, at the same time as removing any weedy regrowth, so the soil is really clean by then end of next year.