Eradicating bishops weed
I am in the Netherlands and we recently bought a house with Bishops weed. As far as I can tell now it is in about half a garden (some flower beds, under birch trees and vegetable garden).
I read through the forums and now know I will have to dig up all the roots and I will do that in contained flower beds. But vegetable garden is completely run over with it and it is just too large to attempt digging and shifting all the earth by hand. Our vegetable garden has a border of buxus hedge. I read somewhere that if you put cardboard and plastic over the land and leave it for period of time it will die. Does anyone know exactly what is proceedure (how long) and material - normal cardboard from boxes and heavy black tarpaulin type of plastic? How long should I leave it under it? Would it help if I put vertical (15" deep) thich plastic sheets into the earth in front of the buxus (on the vegetable garden side) so bishops weed can not spread again to the garden from buxus side? After the covering is removed can I just plant as normal or something needs to be done first?
Just to clarify - I want to keep buxus border and do not want to use any chemicals. I can have vegetable garden in another spot until original one is sorted out.
I know this is a lot of questions but if anyone knows about this method I will really appreciate the advice.