What Are Hormone Weedkillers?

Updated February 21, 2017

Weeds are broad-based leaves that tend to grow naturally in gardens, but are unwanted by gardeners due to their appearance and the space they take up. Hormone weedkillers are designed to kill weeds specifically, making them particularly advantageous for gardeners since they won't kill their other plants. However, hormone weedkillers can damage, though do not kill, broadleaved plants. Unlike most other pesticides, hormone weedkillers have no other detrimental effects on the environment.


Hormone weedkillers are auxin-based selective herbicides, which are pesticides that kill only one specific unwanted plant as long as they're used in the appropriate dosage. As the name suggests, hormone weedkillers target and kill weeds specifically. An auxin is a plant hormone that regulates plant growth. The auxin used in hormone weedkillers are made by chemical synthesis and are the main factor in controlling weed growth.


With hormone weedkillers, you no longer need to handpick annoying unwanted weeds in your garden. They are not toxic for animals or humans, so they're child- and pet-friendly. Hormone weedkillers are preventive weedkillers since they're able to penetrate the ground and kill the roots of weeds inside the soil, so you won't even see them sprouting.


Hormone weedkillers target weeds, but unfortunately, plants that are similar to weeds in terms of being broadleaved can be damaged, but not necessarily killed, by hormone weedkillers. The symptoms that occur in broadleaved plants contaminated by hormone weedkillers include distorted or twisted leaf stalks, swollen stems and warts or galls on the plants. In particular, tomatoes, roses, brassicas, vines, and potatoes are reactive to hormone weedkillers. When used in high quantities, hormone weedkillers cause reduced plant growth and can cause plant death. Thus, it's important to apply hormone weedkillers in quantities suggested by the producer.

Environmental Considerations

Severe exposure to hormone weedkillers did not raise a health risk for birds, fish or any other plant-consuming animals, according to a research study by the Environmental Protection Agency. Because hormone weedkillers specifically target weed growth, they have little or no impact on other organisms. On the other hand, according to North Carolina State University, the use of hormone weedkillers should be avoided near greenhouses since the chemical is injurious to greenhouse plants. To avoid injury to plants, avoid using hormone weedkillers near non-weed broadleaved plants.

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About the Author

Lindsay Haskell began writing fiction and nonfiction in 2008. Her debut novel, "Grace," is to be published in January 2011. Having lived in five different countries and traveled across five continents, Haskell specializes in Third World social and political issues, with a concentration in the Darfur conflict. She is currently a first-year student at Wellesley College studying history, Africana studies and English.