Posted: 27/05/2014 at 20:41
Comfrey , not borage
Borage is an annual that dies off usually in the winter.
Comfrey has a perennial taproot and is really difficult to eradicate,it is propagated by root cuttings, if you leave a piece behind it will regrow.
If you want to get rid, spray the foliage with glyphosate, making sure you dont get it on anything you want to keep.