Roundup is a product created by the Scotts Miracle-Gro Company. It kills many different types of weeds and grass, including thistles. Thistles are flowering plants that have prickles that grow on both the leaves and the flowers of the plant. These prickles hurt if they pierce or brush up against your skin. If thistles are growing your yard, Roundup can get rid of them.
Wait for a day when the temperature will reach above 60 degrees F. It should also be sunny, with little to no wind. This will ensure the best results.
Dress appropriately. Protect yourself with long clothing, boots, gloves, goggles, and a mask. Roundup does contain harsh chemicals.
Remove the handle from the Roundup sprayer, and pump the handle 15 times.
Aim the sprayer within 2 feet of the thistles, and spray until the thistles are soaked with Roundup. Be careful not to get the Roundup on any other type of vegetation. It will kill any vegetation it comes in contact with.
Remove the thistles and throw them away after they die from the Roundup treatment.