How to Mix Roundup Herbicide

Roundup Bioactive is used to effectively eliminate many annual and perennial broadleaved weeds and grass varieties. The herbicide works when absorbed by leaves and green stems. Effects are visible in annuals in 3 to 7 days and in perennials after 2 to 3 weeks. Roundup Bioactive should be applied when the weeds are actively growing to maximise absorption. Effects may be delayed by rainy or windy weather conditions.

Wear protective clothing, including a long-sleeved shirt, socks and shoes, and chemical-resistant gloves. Utilise eye protection and a respirator when mixing or spraying Roundup. Thoroughly rinse external areas of the body that come in contact with the herbicide, and consult a doctor if it is ingested, inhaled or splashes your eyes.

Fill the tank 1/3 to 1/2 full with clean water, as water that contains soil or salt will reduce the effectiveness of Roundup Bioactive. Do not mix the herbicide in galvanised or unlined metal containers. Reactions between the metal and the chemicals can produce a toxic gas.

Turn on the agitator. Measure 10ml for every litre of water used when applying the herbicide for domestic or general farm use. For crop applications, you may need to add ammonium sulphate at a rate of 2kg for every 100 litres (or 2 per cent) before adding the Roundup to the water.

Fill the tank with water once the Roundup has been added and agitate it until thoroughly mixed. Continue to agitate when spraying to ensure that the mixture does not separate. Apply the mixture evenly via a low-volume application with large drops to minimise drift.


The mixing instructions above are for general and domestic use. For use on crops and pastures, see the reference section for tables on mixing ratios and other comments for various plant varieties. You may need to add ammonium sulphate or surfactants to the herbicide mixture, depending on ecological or weather conditions. Positive results may be reduced when the temperature is high or humidity is low.


Roundup will cause irritation to skin and eyes. Wear protective clothing to avoid contact. Herbicides are toxic so store them away from children and animals. Try to minimise drift when spraying. When Roundup comes in contact with other plant species it will cause extensive damage. Use the mixture within five days. Do not contaminate water sources when spraying or rinsing equipment. Do not apply Roundup if the temperature is over 30 degrees Celsius.

Things You'll Need

  • Protective clothing
  • Eye protection
  • Chemical-resistant gloves
  • Respirator
  • Spray tank
  • Agitator
  • Measuring cup
  • Water
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About the Author

Nicole Fotheringham has been a writer since 1997. She was born in South Africa and began as a reporter for the "Natal Mercury" and "Cape Argus" newspapers. Fotheringham has a master's degree in English literature from the University of KwaZulu-Natal.