Mixing instructions for roundup weed killer

Updated February 21, 2017

Roundup Weed Killer is a nonselective herbicide, meaning it will kill any plant to which you apply it. Gardeners can dilute Roundup Weed Killer with water to lessen the strength of the chemical. Apply the mixed herbicide on a still day so that wind does not spread the chemicals onto desired plants near the spraying area.

Read the label of the Roundup Weed Killer completely before you attempt to mix it with water. The label will have dilution rates based on how strong you want the solution.

Fill the reservoir of the gallon garden sprayer 2/3 of the way with clean water.

Measure out the appropriate amount of full-strength Roundup based on the strength of solution you desire. Use a measuring cup to get an exact measurement, then add the Roundup to the reservoir of the garden sprayer. For example, add 20.7ml / 0.7 oz. of Roundup for a 0.5 per cent solution. Add 369gr / 13oz. of Roundup for a 10 per cent solution.

Label the measuring cup with a marker so you do not use it for anything else but mixing the herbicide.

Put the lid on the garden sprayer reservoir and shake the reservoir up and down for 10 to 15 seconds to incorporate the chemical into the water. Attach the hose to the sprayer and apply to the plants according to the package directions.

Things You'll Need

  • Garden sprayer with 1 gallon reservoir
  • Water
  • Measuring cup
  • Marker
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Based in Richmond, Va., Dawn Gibbs writes about topics such as history, fashion, literature, crafts, alternative medicine and healthy living. Her work has appeared on and several style websites. Gibbs holds a Bachelor of Arts in history from Virginia Commonwealth University.