How to Use Diatomaceous Earth in Your Garden and Home

Diatomaceous earth is a virtually harmless, natural, and effective pest control option for use in the home and garden. Knowing how to use it can make your life much easier. And who doesn’t want an easier life?

Diatomaceous earth, or DE, is made of fossilized aquatic remains ground to a fine, smooth-textured powder. It’s a bit irritating to humans and animals since it’s a dry dust that can get in your eyes or make you cough. But the food-grade form is non-toxic and used to fight off insects in your home.

Let’s take a look at the good and the bad of diatomaceous earth and how you can start using it in your garden.

What Is Diatomaceous Earth?

Diatomaceous earth is a white powder made of fine particles. Since it looks like dust, it’s hard to believe it’s made from the fossilized remains of aquatic organisms! The organisms were diatoms, a specific form of phytoplankton that is a type of algae. The cell walls are made of silicon dioxide.

Over hundreds of years, diatoms built up in bodies of water and became fossilized over time. They formed a siliceous sedimentary rock called diatomite that can be ground into a fine powder. That’s the powdered form we refer to as diatomaceous earth. 

How Does Diatomaceous Earth Work?

How will diatomaceous earth kill insects if it’s just a powder? We can’t see it or feel it as we have much tougher skin that isn’t damaged by it. But these microscopic particles of diatom shells have sharp edges that cut into an insect’s exoskeleton as they walk over it.

The diatomaceous earth then sticks to the insects. Because the powder is so dry, it will absorb the moisture from insects (such as fats and oils) and cause them to dehydrate. It sounds gruesome, but it’s just nature working.

The downside of DE is that it has to be dry to be effective. If you apply it to your garden and it rains, or you water your plants, it will no longer be effective until it fully dries again. 

Types of DE

You should always use food-grade diatomaceous earth. This kind of diatomaceous earth is purified and sterilized, doesn’t have any harmful additives, and is considered amorphous silica generally recognized as safe by the FDA. 

Food-grade DE is found in various products outside of gardening. It’s listed in toothpaste, beverages, skin care products, animal feed, medications, rubber, and many other things. It’s completely safe to use in both your garden and in your home. However, it is drying, so you’ll need to wear PPE when applying it.

It is often used to prevent insects from eating livestock feed. You can find it at your local feed store or garden center, often labeled as diatomaceous earth for pest control. Buy diatomaceous earth labeled as feed-grade DE or food-grade, not as pool-grade.

There’s another type of diatomaceous earth that isn’t as safe. This kind is crystalline silica, which may cause lung disease, inflammation of respiratory systems, and potentially even cancer if it’s inhaled.

This kind of DE is found in few products meant as pesticides. Sometimes, it’s sold as pool-grade diatomaceous earth, used in swimming pool filters or non-potable filters. Pool-grade DE is treated with high heat to crystallize it rather than leave it in its amorphous form.

The labels will usually have a warning label to let you know that it’s not safe for human consumption. Avoid any diatomaceous earth that describes itself as crystalline silica.

Benefits

Diatomaceous earth can kill almost any insect with an exoskeleton, including ants, aphids, bed bugs, cockroaches, flea beetles, fleas, carpet beetles, and spider mites. It can even kill snails and slugs, too.

Diatomaceous earth will only kill the adults or larvae of these pests, not the eggs. But disrupting the lifecycle and killing adults before they can lay eggs limits populations.

You’ll have fast results as it starts working instantly, as long as it’s dry. It can take up to twenty-four hours for the bugs to die, but the dehydration process begins as soon as they make contact with the powder. 

A benefit of food-grade diatomaceous earth is that you can use it inside and outside of your home. Apply diatomaceous earth directly on ants, along baseboards and windowsills, on the soil outside, on the leaves and branches of plants, or wherever else you need it. 

If your pets have fleas, apply diatomaceous earth to the carpet, rugs, and pet beds. This eliminates the adult fleas and prevents them from laying more eggs. Keep your dogs or cats away from their bedding while you treat it as the dust is an irritant when inhaled. Leave the diatomaceous earth in place for at least 8-12 hours before thoroughly vacuuming.

Food-grade diatomaceous earth is non-toxic to humans and animals, although it can be an irritant. Luckily, the risks are minimal.

Drawbacks

The biggest drawback of diatomaceous earth is that it can be an irritant when inhaled or when it gets into mucous membranes. It’s generally considered safe to use around kids and animals. However, breathing it in can cause lung irritation, shortness of breath, and coughing. It can make your skin and eyes itchy and dry, too. 

Remember, food-grade diatomaceous earth is the safer version of DE. Non-food-grade forms meant for pool or other uses are comprised of crystalline silica. They have many more potential health risks than the food-grade version does.

Another drawback is that DE has to be dry to be effective. Daily watering, heavy dew, and frequent rain can make using DE a hassle. It won’t be as much of an issue inside the house, but outdoor garden use requires forecast checking and planning in advance.

DE is also not only harmful to bad pests. It may be harmful to beneficial insects that act as pollinators, including bees and butterflies. You can avoid harming them by paying attention to how and where you apply the powder. Pollinators almost always land on flowers, so avoid putting DE on any part of the flowerhead. 

If you’re worried about accidentally hurting your pollinators, take a few days to observe how they move around in your garden. Take note of where they land, which plants they gravitate toward, and what time of day they’re most active. Minimize the risks by avoiding certain plants and flowers. You can also try alternative pollinator-safe pest control methods first.

How To Use Diatomaceous Earth

Using diatomaceous earth is super simple, but there are a few things you should know before you start. Always use food-grade DE, wear protective clothing and gear when applying, and always read the label before you start.

Wear a dust mask, safety goggles, long-sleeved clothing, and gloves when using it (even if it’s food-grade) to prevent yourself from inhaling it. Keep children and pets out of the area until the dust has settled completely.

Even though most DE is the same, you should still read all the label directions before you use the product. Some brands may have different directions than others. This is especially important since there are other forms of DE that aren’t food-grade. If you accidentally bought the wrong one, reading the label will stop you before you apply diatomaceous earth of the wrong kind!

How To Use DE In The Garden

Since water softens amorphous silica and renders diatomaceous earth temporarily useless, it can be somewhat tricky to use in certain situations. But that doesn’t mean it can’t be used at all!

Don’t apply it when the ground or plants are wet. Keep it away from areas that collect runoff water. Unfortunately, this means it’s not very effective around plant roots, so you’ll need to use a different method to get rid of bugs that live directly in the ground.

To apply diatomaceous earth when it’s dry, sprinkle it where you need it or use an applicator. Sprinkle it on crops, on the ground, on the patio, in obviously infested areas, or wherever you need it. Sifters help you get an even application, and dusters make it easier to apply a fine layer to the leaves of plants.

Spray

It’s also possible to mix diatomaceous earth with water and spray it. This is the easiest way to adhere DE to hard-to-reach areas of plants. Wet diatomaceous earth will stick to the plants and become effective once it dries out.

The label on your bag may have specific measurements to make a spray. If it doesn’t, four tablespoons per gallon should do the trick. 

If you choose to apply diatomaceous earth spray, make certain that your specific brand recommends applying DE in this fashion. Some versions are not as finely powdered and may include larger natural particulates. This can clog your sprayer and make it hard to re-apply.

Soil

Soil application can be tricky, particularly if you use a watering method that soaks the ground around your plants. People using soaker hoses may have a leg up on this process.

If you get your soaker hoses in place permanently, then top with a thick layer of mulch, you can apply diatomaceous earth on top of the mulch. The mulch acts as a natural moisture barrier and keeps your diatomaceous earth drier and more effective as a result. 

How To Use DE In The Home

Sprinkle dry diatomaceous earth in areas where you see pests the most. This can be under appliances, on windowsills, under beds, along the door frames or baseboards, or wherever else you see it in the house. Work it into crevices between floorboards, too.

If you have children or pet animals, keep them out of the area until the dust has settled. Keep an eye on them to make sure they don’t try to eat it. Avoid application near the heater or air conditioner vents to prevent the powder from becoming airborne.

Use a fine flour sifter or a duster to evenly apply DE on carpets and rugs. It will last a long time indoors, so you won’t have to reapply often. When you’re done treating the floors, vacuum the dust and dead bugs up.

Apply diatomaceous earth to beds to treat bed bugs, pet bedding, blankets, cushioned furniture, or wherever else you find pests hiding. Be careful when you treat these areas as the dust can be irritating. Don’t use the furniture or blankets until you’ve completed the treatment and thoroughly washed all items, or vacuumed all surfaces.

The wet application isn’t viable to use indoors, although you could probably use it in garages or on tile floors. Allow the area to dry on its own so the diatomaceous earth can dry. As it’ll be messy and humid for a bit, it’s better to stick with dry application methods indoors.

Frequently Asked Questions