Why Does My Roundup Clump Up in My Jug?

Storage

• The product’s instructions suggest clearing the pump and closing the pump release after each use. If the pump is not empty and the pump release tab is not closed, fumes can escape and evaporate. If the ingredients are not proportionately correct, it may cause the solution to clump or become less effective.

Temperature

• Roundup should be stored in a cool, dry place. If the product is stored in direct sunlight or in freezing temperatures, its storage environment can affect it. Freezing temperatures will cause the active ingredients to separate, which may cause crystallization, according to the University of Florida. Heat can cause the ingredients to evaporate.

Age

• Roundup is used in climates that allow weeds and other shrubs to grow. If unused Roundup is stored during seasons when plants, grass and weeds don't grow, it can cause clumping over time. The active ingredient may evaporate or deteriorate during storage, depending on the product’s age and how it’s stored. If the Roundup is several years old from the time of purchase, it can clump from deterioration.

Solution

• Ensure the Roundup container is sealed after each use. This process includes draining the solution out of the pump completely. Store the product in a temperature-controlled environment such as a basement or closet. Storing the product in a shed or garage may overheat or freeze the product. Not only will the product clump, it may render it useless because of separating the ingredients.