Kaolin Clay in the Garden: Natural Pest Control

Pests are part of gardening. While they can be discouraging at times, it’s often a sign that you’re doing something right—if the bugs won’t eat your food, why would you? Even if a sign of life is good, they can quickly overstay their welcome and become a problem.

There are plenty of options on the market, but some of them contain harmful chemicals, while others aren’t guaranteed to make a difference. This is where kaolin clay comes in. It’s a completely natural product that seems like it works miracles.

This powdery clay is mixed with water and sprayed on plants to physically prevent pests from attacking your garden. It’s most commonly used on fruit trees but can work on just about any plant. It doesn’t harm plants and can even protect them from getting sunburnt. 

This natural pest fighter is growing in popularity among gardeners. If you haven’t jumped on the bandwagon yet, I’ll probably convince you to do so with this article! It’s an affordable pest control option that will help you greatly reduce, if not completely eliminate, a variety of pests plaguing your garden.

What is Kaolin Clay?

Kaolin clay is a white, powdery type of clay originating on the Kao-ling hill in China. Kaolin exists throughout the world. In the US, it is mainly in Georgia and scattered throughout the southern states.

This clay is predominantly made up of a mineral called kaolinite, but it also contains quartz, feldspar, and a few other minerals. As a mineral product, you can be sure that this is an all-natural pest control method, provided it has no extra additives.

What is it Used for?

Kaolin clay has many uses outside of the garden. It’s a frequent exfoliant in skincare products such as face masks. It has multiple industrial uses, like in the production of paper, paint, rubber, and porcelain.

In the garden, kaolin clay is most commonly used as a form of pest control, but it can also be used as a plant sunscreen that can help improve how light is reflected in the garden.

Pest Control

Rather than killing pests on contact, the kaolin coating confuses insects, and they won’t land on the plant. This method works for various insects, including the troublesome Asian citrus psyllid, the leading pest that causes the citrus greening virus that plagues many orchards.

According to the University of Florida, the Asian citrus psyllid locates fruit trees by sensing light wavelengths we perceive as yellow or green. When leaves and fruit are covered in powdery kaolin, the light wavelengths the pests are looking for don’t show up, so they won’t land on the trees.

Since you’re covering up the plants with powder, you’re also making it physically impossible for sap-sucking insects to feast on your plants. They’d have to go through the kaolin barrier, and if you applied it sufficiently, it would be difficult for the bugs to do. So, not only are you confusing pests in the first place, but you’re also making your plants play hard to get, so it’s kind of like you get two forms of defense in one product.

Impact on Beneficial Insects

Kaolin clay is considered safe for beneficial insects, but there are a couple of things to keep in mind. First off, it messes with the bugs’ detection abilities, so you may inadvertently tell the good guys to “buzz off” by covering up the plants. If you want to spray, be sure to keep a clay-free pollinator garden nearby so the bugs can have a home within flying distance of your garden. 

Second, if you spray the clay on flowers, pollinators can’t do their job because you’ve covered up the pollen. Be sure to apply the kaolin before or after flowers appear so you can be sure to give bees and friends proper access to what they need.

Protect Against the Sun

Humans aren’t the only ones susceptible to burning in the sun; plants can do it, too. If you live in a hot climate like I do, you’re probably no stranger to seeing crispy leaves after a heatwave. Just as you put on sunscreen before stepping outside, you can use the clay as sunscreen for your plants.

Covering the leaves and fruit in clay prevents light wavelengths from showing up for critters’ sensors, meaning the sun’s light can’t penetrate that barrier, either. When the intense rays can’t hit the leaves, it will prevent them from burning, and you can protect your plant through the hottest days of summer.

Improve Lighting

A third garden use is to help light diffuse better throughout the garden. You may have heard that wearing white in the summer helps reflect light while wearing black will soak up the light and make you hotter.

The powdery white clay works similarly; it helps light bounce off the leaves and reach places it may not have had access to before. This “bonus” sunlight may help your plants grow better.

Prevent Pests

Using kaolin clay as a bug-battling tactic is simple. Although it’s a powdery substance, you can apply it by spraying it onto your plants in liquid form. Once it dries, it starts doing its job.

Create a Sprayable Liquid

Always check the packaging of your kaolin clay to see if there are specific directions. Unless stated otherwise, three cups of clay to one gallon of water is a standard measurement. The consistency you’re looking for is a liquid you can spray with a sprayer, like the Venus 2L Hand Held Pump Sprayer. If you’ve created a paste, you need much more water.

If you’re working on a very small scale, you can eyeball your measurements with a spray bottle. Add a scoop or two of powder, fill it with water, and give it a shake. Directions online are often provided in large quantities since it’s a common practice in large orchards.

However, you don’t need to worry too much about converting measurements for one gallon down to a few ounces. As long as it sprays and leaves clay behind when it dries, it should work out fine.

Apply the Liquid to Your Plants

Kaolin clay is non-toxic to plants, so you can spray it as needed. Remember that the goal is to prevent pests from landing on the plant, so spray wherever pests land. Spray the clay on stems, branches, twigs, and the tops and bottoms of leaves.

You can even spray fruit once it sets, but avoid spraying flowers. Doing so may prevent pollinators from doing their jobs, which will reduce fruit production.

Dry Kaolin Does the Job

Apply a new coat of kaolin once a week or after it rains. Kaolin won’t stick to plants forever and will wash off when wet, so frequent applications will be necessary for it to remain effective. 

The dry powder is what prevents insects from landing on the plant. If you get kaolin-coated leaves wet while watering, pests may infiltrate your plant from this weakened state. It’s inconvenient to reapply daily, but a small spray bottle may help for mid-week touch-ups while you wait for the weekend to reapply. Consider removing the lower leaves from your plants so you can reduce water splashing onto leaves.

Safety Guidelines

Kaolin clay is non-toxic and safe for you and your plants, but there are still some safety precautions you should take before you start working with it. The fine powder could be an irritant if it comes into contact with your eyes or if you inhale it.

Wear safety goggles and a mask while you mix up the dry powder and spray it onto the plants. Avoid using it around others, especially if it’s windy outside. In general, do full applications every seven to ten days, and only touch up if needed between then.