Posted: 06/09/2015 at 18:21
Try and dig out as much as you can. The roots go extremely deep and you won't be able to remove them all though. When it grows back, you can either keep pulling it up, or spray with glyphosate which will eventually kill it. It isn't as bad as you might think - I've moved clumps from one part of my garden to others and it does eventually give in.