I’ve been reading about getting rid of ground elder and couch grass in particular. Ground elder leaves are edible according to the book “Edible Plants” from Plants for a Future. Couch grass is the most difficult apparently.
In one of these two books, they reccommend covering the ground with hedge clippings, or woody clippings which lay more or less flat. Then newspapers – whole ones in an overlapping patchwork, and then flattened cardboard boxes. Follow this by old carpet (must be made of natural fibres though).
After this, you can mulch with woody trimmings again, followed in any order by these three — wood chippings, then compost, then your growing medium and use these three layers to create the top surface you want. So I would end with the woodchips on the top.
If I understand it corrrectly you can grow straight into the top of the 6 or 9 layers.
Couch grass can survive for a year underground apparently so is by far the most difficult to defeat.
The book says that Ground Elder has a very long history of edible and medicinal use, it was cultivated for both in the Middle Ages. Leaves have an unusual tangy flavour, can be served in salad or cooked as spinach. Used a great deal to treat gout and counteract the highly rich diet of monks and clergymen.
Hope this helps. The other book is called “Plants for a Future” by Ken Fern. Both are admirable and appear to cover most if not all edible and useful veggies and flowers. Both cheap from Amazon.
Good luck.
Julie