Will Borax Kill Plants? Discover The Truth Here!

When it comes to gardening, it’s essential to maintain healthy soil to ensure the proper growth of plants. However, sometimes plants are susceptible to pests and diseases, and gardeners opt for chemical treatments. But what if you could use natural remedies to protect your garden? One such remedy is borax. But the question is, will borax kill plants, or is it beneficial for them? Let’s find out!

What is Borax?

Borax is a naturally occurring mineral that contains boron, sodium, and oxygen. It’s usually found in dry lake beds, but it’s also mined from the earth. Borax has various industrial applications, such as in the manufacture of glass, porcelain, and insulation. However, many people use borax as a natural cleaning and pest control solution.

How Does Borax Work?

Borax works by disrupting the metabolic process of plants, insects, and fungi. It interferes with their ability to absorb nutrients and water, leading to their eventual death. It’s also abrasive, making it an effective cleaning agent. However, borax is only effective in small doses, and a high concentration can be toxic to both plants and animals.

Is Borax Safe for Plants?

As with any chemical or natural remedy, the impact of borax on plants depends on its concentration and usage. In small doses, borax can be beneficial for plants as it contains boron, which is an essential micronutrient required for their growth. Boron helps strengthen cell walls, aids in root development, and promotes flower and fruit growth. However, an excess of boron can kill plants, leading to yellowing and browning of leaves, and stunted growth.

Benefits of Using Borax for Plants

When used in moderation, borax can benefit plants in several ways:

  • Boosts plant growth: Boron helps plants absorb other essential nutrients, such as nitrogen, phosphorus, and potassium, making them grow faster and healthier.
  • Controls pests: Borax can be used to get rid of pests like ants, cockroaches, and silverfish that damage plants.
  • Prevents diseases: Applying borax to the soil can prevent fungal diseases like powdery mildew and rust that affect plants.
  • Improves soil quality: Borax helps maintain the pH level of the soil, making it more alkaline, which is beneficial for certain plants.

How to Apply Borax to Plants

There are different ways to apply borax to plants, depending on the desired outcome:

  • As a fertilizer: Mix one tablespoon of borax in a gallon of water and spray over the leaves of the plant.
  • For pest control: Mix borax with sugar and flour in equal parts and sprinkle it around the base of the plant.
  • As a soil amendment: Mix 1-2 tablespoons of borax in the soil around the base of the plant. Avoid getting it in contact with the roots.

Is Borax Harmful to Plants?

While borax can be beneficial for plants in small doses, an excess of it can be harmful. As borax disrupts the metabolic activity of plants, a high concentration can lead to their death. Additionally, borax can accumulate in the soil over time, making it toxic to plants. Plants that are particularly sensitive to boron include citrus, beans, and strawberries. So, it’s crucial to use borax in moderation and observe the impact on plants before continuing its usage.

Signs of Borax Overdose in Plants

If plants are exposed to excess borax, they may exhibit the following signs:

  • Yellowing or browning of leaves
  • Stunted growth or no growth at all
  • Dry, brittle leaves that break easily
  • Brown spots on leaves


So, will borax kill plants? The answer is, it depends on how it’s used. In small doses, borax can benefit plants as it contains boron, which is essential for their growth. It can also be used as a natural pesticide and fungicide. However, a high concentration of borax can be toxic to plants, leading to their eventual death. It’s key to use borax in moderation and observe the impact on plants before continuing its usage.

Common Questions and Their Answers

  • Can I mix borax with fertilizer?

    Yes, you can mix borax with fertilizer. However, don’t mix it in high concentrations as it can harm plants.

  • Can I use borax on all plants?

    No, some plants are particularly sensitive to boron and can be harmed by its usage. These include citrus, beans, and strawberries.

  • Is borax toxic to animals?

    Borax in high concentrations can be toxic to animals, particularly to cats and dogs. Keep borax away from them and out of their reach.

  • Can I use borax to control weeds?

    No, borax is not effective in controlling weeds. Instead, use organic weed control methods like mulching or hand removal.


  1. Borax – Uses and Benefits, November, 2021, Retrieved from https://www.almanac.com/fact/borax-uses-and-benefits#:~:text=In%20small%20amounts%2C%20borax%20is,for%20both%20plants%20and%20animals.
  2. The Effects of Boron on Plant Growth, November, 2021, Retrieved from https://homeguides.sfgate.com/effects-boron-plant-growth-31582.html
  3. Borax – What You Need to Know, November, 2021, Retrieved from https://www.healthline.com/health/borax#safety-and-precautions

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