There is a wide variety of thistle including musk, star, sow, field and milk thistle, to name but a few. Although they may look harmless, they are amongst the most competitive plants, depriving other plants of much needed water and nutrients from the soil. It is so bad that entire groups have banaded together in order to remove it from national parks. If you are stuck with a thistle problem then it is time to get rid of it.
Mow more often
Mowing is the method of choice when you want to get rid of a large amount of thistle. As you cut the plant each time the root eventually becomes starved of nutrients and the plant dies. The seeds cannot be forgotten, since when you cut the plant they are left behind. Always be sure to clean them up as well to avoid new thistle from growing. The best time to cut thistle would be at the flowering stage, and this should be repeated several times over the next month. For creeping thistle you can cut some off and then mow it.
Rooting it out
Cutting the plant numerous times can be a tedious task for anyone. A good way to get rid of it faster is to get to the root of it all. Try as far as possible to dig the thistle up when it is still in its early stages of growth. Make sure that you have removed the entire roots system to ensure it doesn’t grow again. If roots are left in the ground it can even lead to multiple plants sprouting off of a single root.
Remove the light
Thistle thrives best in lots of sunlight so a good way to kill them is to remove the light. You can simply cover them with a sheet of metal, cardboard or tar paper to prevent sunlight from getting to it. The plant will eventually die out. The only problem here is if the thistle is amongst other plants those plants will die as well, since they need sunlight to survive as well.
Burn it up
Burning thistle to get rid of it should be a last resort. It is not simply a matter of setting it alight and watching it go up in flames. There are many things to consider. Your best bet would be to get a professional in so that it can be done properly.