When it comes to deep rooted spiky weeds like thistle I like to use a knife or clippers and cut them off at ground level. They will resprout so you must cut them again and than a third time if the root has not dried out from the first two beheadings. I also recommend wearing leather gloves with long sleeves like the type rose growers use for pruning roses. This difficult job is best performed with a determined group of gardeners, perhaps music playing and a hot meal or cold drink waiting after the thistle battle is over. You can do it! Keep growing, (but not thistle), Marianne Binetti