Clearing out to start again...

Apply the roundup before strimming! The weeds absorp the chemical through their leafs and down into the roots. Give it a couple of weeks, you'll need at least two applications to kill ground elder.

Roundup won't affect roots as it becomes inert as soon as it touches the soil. It will kill anything green, so avoid spraying anything you want to keep. Read the instructions carefully and avoid spraying on a windy day for example, where the drift may kill off your neighbours plants.

 

Roundup is the best for that job. Roundup is actually a trade name so you can buy the same weedkiller (active ingredient glyphosate) under other brands names, much cheaper, e.g: from Wilkos

 

I would do the same as John says too, patience and thoroughness getting rid of the weeds now will pay off later..

 

They should be the same, the thing to check is the concentration:

Wilkos:

at £10/l

Whereas the Wilkos Roundup is:

at £4.50/l

http://www.wilko.com/weed-killers weed-guards/roundup-fast-action-weedkiller-1ltr/invt/0100877

So the Wilko brand is much cheaper going by the amount of active ingredient - but not so convenient as you'll need to dilute it and add it to a sprayer. Swings and roundabouts

 

There are organic alternatives to Roundup of course, such as digging/weeding by hand or you could cover the area with old carpet to exclude light - it might take a year but it will eventually kill off even ground elder.

 

I think most of us do but if you have a small urban jungle on your hands which it sounds like he does and not too much time, weed killer first then start the thorough digging process is the way I think.. By the time you have finished digging & put some manure or the like back in it will be good soil....