Wear Protective Clothing
Wear protective clothing such as gloves, eyeglasses, a long-sleeved shirt, long pants and closed-toe shoes to prevent contact of the toxic herbicide with your skin in case of accidental drips, spills or sudden change in wind direction. Spread a tarp, cardboard or plastic sheet over any desirable vegetation near the ones you want to kill, as the herbicide kills anything it comes into contact with. Cover completely so no part is visible at all.
Apply Roundup to weeds when they are actively growing so the herbicide penetrates visible vegetation growth and prevents the plant from producing essential amino acids needed for growth. Although the rate at which the herbicide is applied usually varies according to the type of weed, it is typically applied in spring, or from February through April, before the noxious pests produce and spread seeds. Select a clear, warm and dry day for application, with no chance of winds or rain for up to 24 hours after application. Heavy rainfall immediately after application dilutes the Roundup application on unwanted vegetation and reduces the efficacy of the herbicide.
Roundup is available in both concentrated and ready-to-use forms. Dilute the concentrated formula according to label directions, or pour cool water to a tank sprayer along with 3 fluid oz. of the concentrate per gallon, or 1.5 fluid oz. of the super-concentrated formula per gallon. The ready-to-use formula comes with its own built-in spray applicator. If it lacks one, pour the amount into a garden sprayer. On average, you need 1 gallon of herbicide for every 300 square feet of area.
Aim to achieve direct contact with the undesirable vegetation. Limit distance to 10 feet from the tip of the nozzle to the tallest plant; and bend down slightly if you want to maintain good contact with target plants. Position the nozzle directly over the plant or weed and spray over it to completely cover the foliage. Avoid over-spraying as runoff only wastes the herbicide. Depending on the type and size of weed, and the outdoor and soil temperatures, most weeds die in three days to two weeks.
Prevent children or pets from going to the area sprayed with Roundup until it dries. Discard clothing heavily drenched with the Roundup herbicide or soak protective clothing with soap and hot water to remove trace elements. Wash yourself thoroughly with warm soapy water. Store the herbicide in a safe place, away from reach of children and pets.