Gardeners are often given the advice to sprinkle diatomaceous earth (DE) around plants to deter pests. Unsurprisingly, we’re often asked, “What is diatomaceous earth, exactly?” Well, here’s your answer…
What Is Diatomaceous Earth?
Diatomaceous earth (DE) is the fossilized skeletons of microscopic single-celled aquatic organisms called diatoms. Their skeletons are made of a natural substance called silica—which makes up 26% of the Earth’s crust by weight.
Deep deposits of diatomaceous earth are mined in the western United States in places where lakes once covered the area millions of years ago.
How Does Diatomaceous Earth Deter Garden Pests?
Snugs and snails do not like to crawl over DE because the silica skeletons are very sharp—like tiny pieces of broken glass. (Slugs and snails don’t like eggshells either!) If their soft bodies do get cut, they eventually dehydrate and die. This process works on other soft bodied insects, too, including caterpillars and aphids, as well as on those with hard shells, such as beetles, fleas, cockroaches, and even bed bugs. The tiny particles of DE get into the insects’ joints, causing irritation and dehydration.
Caution: The downside to DE is that it does not discriminate between pests and beneficial insects. Ladybugs, green lacewings, butterflies, bees, and other “good guys” can also be killed by DE if they come into contact with it. For this reason, we recommend using DE with discretion on and around plants that beneficial insects may frequently visit. Avoid using it around flowers as well.
How to Use DE
- When shopping for DE, look for the “food grade” quality. The DE used in pool filters is not effective against garden pests.
- Sprinkle bands of DE around the plants you are trying to protect. It’s important that the ring of DE does not have any gaps for pests to sneak through.
- If pests are eating the leaves of your plants, you can dust the leaves with DE, which should discourage further damage. However, you should avoid applying DE near the plants’ flowers, where pollinators might inadvertently come into contact with it.
- When using DE, it’s recommended to wear eye protection and a dust mask, as the small particles can be irritating.
- DE works best in dry conditions. It clumps together when wet, so reapply after it rains.
Is DE Safe to Use?
Even though the industry states that this product does not cause lung damage, I would still refrain from breathing it in. Remember, it might feel soft to the touch, like talcum powder, but it still is an abrasive and can cause irritation to your eyes, nose, lungs, and throat. Wear a dust mask and eye protection when handling it just to be on the safe side.
Food-grade DE is not toxic if ingested in small quantities. In fact, we probably have been eating it for years unknowingly, since it is often mixed with grain in storage to kill insects. It can also be found in toothpastes and skin care products. Some people take it a step farther and use it for treating internal parasites! However, the DE that is commonly used in pool maintenance is not edible.
DE does not harm the soil since it is made from silica, the same as sand and many rocks. It does not break down when exposed to sun. Rain can wash it into local water sources but it is non-toxic to fish and other aquatic life. It is not harmful to birds or other wildlife. It has been added to livestock feed for years.
If pests are enough of a problem that you would be tempted to resort to a chemical pesticide, give DE a try first. It is considered organic by the Organic Materials Review Institute (OMRI) and the National Organic Program considers it a non-synthetic and permits it use in crop production.
See the Almanac’s Pests and Diseases Library for more advice on solving gardening problems.
Reader Comments
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big black ants
Never had this problem before: I have big black ants 1/2" interfering with my okra set. They get on the base of the flowers and the flowers can abort the fruit or disfigure the pods. Will diatomaceous earth at the base of plants keep them off?
Diatomaceous Earth
If you have gnats flying around your house and can't figure out where they're coming from and have indoor potted plants, try this. Just sprinkle it on top of the soil and you will be rid of those pesky gnats. Fungus gnats lay their eggs in the soil and then hatch out and the cycle goes on and on. I also use it on my four dogs as a natural flea powder, works great.
Earthworms
Will DE harm all the earthworms in my garden? I always have a problem with slugs and cabbage worms in the spring and squash bugs on my zucchini. I would like to try DE but have always been hesitant.
DE does not harm earthworms;
DE does not harm earthworms; they can actually eat it. Many worm farmers sprinkle DE on the surface of their worm bins to control fruit flies and fungus gnats.
DE
I have used Food Grade DE many times on the Feral Cats I feed. There's a patch of dry dusty dirt close to where I feed them. I sprinkle DE on the ground & then add a bit of Catnip & they roll in it. Covering themselves with DE to kill Fleas! They are all Black Cats & look Hilarious covered in White Dust! I also mix it into their food to help with Parasites! I sprinkled it on my Carpet & brushed it in when I was Fostering a Feral Mama & her Kittens in my spare bedroom. No Fleas got past that room!
DE edibility WARNING!
This article states that DE is edible. FOOD GRADE DE is edible. The stuff used in your pool IS NOT! Pool Grade is heat-treated to make it a better filtering agent. It also turns the silicone dioxide in the DE to crystalline silica, which CANNOT be eaten!
Food-Grade DE
Yes, you are correct! We’ve made this more clear in the article.
DIATOMACEOUS EARTH
I use DIATOMACEOUS EARTH in my chicken coop it helps with the odor and keeps the nasty flys away. Also mix it in the chicken feed as a natural dewormer. I have also dusted the baseboards of our home when we had a flea problem as well as dusting the dog.
Pollinators and mix ratios
Thank you for this article. I see that the recommendation to avoid killing pollinators is to avoid flowers and flower-surrounding leaves, which makes perfect sense. If one practices this, there must be an optimum dilution for aerosol application to minimise damaging pollinators and plants. I see that others have requested this. Is there a recommendation?
DE Works!
I use DE in my garden to get rid of slugs and snails; it works! I also use it to keep cutworms and pillbugs away from tender transplants and seedlings. It works!
However, I always use it as a powder. Will you please inform me of the proper ratio of food-grade DE to water for spray applications?
Thank you!
I’ve seen it mixed in a
I’ve seen it mixed in a recipe of 2 cups of DE in 1 gallon of water. If that gums up your sprayer you can dilute it even more.
DE effectiveness when wet
Please specifically address the issue of food grade DE's effectiveness when wet. One reader posts that she mixed it with water and sprayed. She said it was thus effective. Is it that when it dries it's effective? I've also read that it can be used as a wormer for goats, cats, dogs, etc. by mixing with their food. How does it work for that when the gut environment is wet? I'm confused by seemingly conflicting information. . . . Thank you.
Wet DE
I am not fully sure how it works, but it does. I rescued a puppy and she had worms. I already mix DE in my coffee and water daily, so I mixed it into all of my dog's food (I had 3 dogs but they all caught worms from the new puppy). I mixed it into their food daily and within 30 days the worms were gone. I took her to the vet to confirm it and she came back clean as a whistle. I still mix it into their food and to this day they have not had worms again.
I used DE in my vegetable garden all the time. I use it especially in my squash ( zucchini and butternut ). I spray it on the underside of the leaves and all over the plant, when it drys your plant will look like there is white powder all over it, that is the DE. I also mix seventh generation dish soap and DE in a spray bottle and when I see squash bugs, or newly hatched squash bugs, I just spray directly on them and they will die in an instant.
I am no scientist, but I know when something works and this works. I pray you get the response and understanding that you are asking for. Have a blessing filled day.
Boxelder infestation in my boxwoods and hydrangeas
Hi! I have an infestation of boxelder bugs in my boxwood hedges and my hydrangeas. Would you recommend sprinkling DE directly onto the bushes? Thanks!
DE Insecticide vs Food Grade
What is the difference between using food grade DE vs. DE insecticide? How is it different? I'm not using it directly on any animals. I want to use it for inside out ants outside ants Japanese beetles and other garden pests. I do have a young child cats and possibly will be adding a dog.
Food-Grade DE
The DE that’s used as an insecticide is typically the same as the food-grade substance, but it may vary by product, so be sure to check the label for warnings. The DE products that you DON’T want to use are those made for use in and around pools, as they usually contain added chemicals.
Food-grade DE is safe to use with pets and children, but if it’s consumed in large quantities it can be harmful. Only use small amounts in specific areas and be sure to keep the bag out of reach of kids and pets.
DE Uses
We used it to get rid of bed-bugs in our home. Also, any invasive bugs that crawl into our home.
Does DE kill iris borer?
I have heard that DE kills iris borer. If so, how is it applied?
Sprinkle it around the
Sprinkle it around the rhizomes in early spring when the caterpillars hatch out and go looking for iris foliage to eat or in late summer when they leave the dead rhizomes and head for the soil to burrow in and pupate over the winter. Finely ground eggshells will work too.
Diatomaceus earth
I wanted a natural pest control for my yard this year. I bought food grade DE. The directions said to mix it with water and spray it on. It killed every bug within yards of my property. The bees were gone unfortunately, flies and knats were gone, and it killed all the blossoms on my azalea bush. I also started getting ants on my kitchen counter and sprayed a little of it around my outside foundation and haven't seen an ant since. I will use it again, but more spareingly. I don't want to kill the good insects and bees.
DE is an indiscriminate
DE is an indiscriminate killer so beneficials will be killed along with the bad bugs. You need to use it sparingly. To lessen the impact on bees and other pollinators, avoid spraying it in or near blossoms. Apply it in the evening when most pollinators are not active. If it was applied heavily to your azalea blossoms it probably dried them out.
Effective Horn Worm Combatant
Our tomato plants were overrun with horn worms this year, so we tried diatomaceous earth before resorting to chemicals; it worked great—saved our crop this season. Highly recommend!
D.E.
There are outcrops of DE along roads in my neck of the woods. I'm guessing the raw product from these outcrops is just as good our better than the store bought?
Maybe not. The finer food
Maybe not. The finer food grade DE is the most effective.
Safe for cats?
I just saw a video which recommended sprinkling catnip on D.E. to lure cats into rolling in it. The D.E. is supposed to destroy fleas. But this article warns against the potential hazards of airborne D.E. and its affect on lungs. Is this safe for cats or not?
Food grade DE has smaller
Food grade DE has smaller particles and lower silica content. It is the silica that eventually damages your lungs. I always err on the side of caution which is why I would recommend that you wear a mask when using DE just in case. Many pet owners swear by it for flea control on their cats and dogs. It does dry out their skin so it is also recommended that you bath them after a few days to wash it off. I have never tried bathing a cat, have you?
Diatomaceous earth
My container of DE said to mix it with water and spray it on my plants and underneath them. It got rid of every bug, flying and crawling, in my whole yard. I had ants getting into the kitchen through the outside wall. I sprayed it outside of the wall and haven't seen an ant since. One caveat, don't spray it on flowers or blossoms. It kills them too.
DE
Had some house guests who had recently moved to a new apartment. Unbeknownst to them, their new apartment had bed bugs. Needless to say, by the time they left our house, we had bed bugs too. Had the exterminator out three times at a cost of well over $300, all to no effect. The bed bugs persisted. Got some Diatomaceous Earth, and spread it in all out dresser drawers, around all the baseboards, and around the headboard of the bed. (Bed bugs nest in wood, and only get into beds to feed on teh people sleeping there.) We left the DE there for four weeks (bed bug eggs gestate for three weeks), and have not had an issue since.
DE
Will it kill stink bugs? They have been terrible this year in my garden, and I am just thinking about how to have a better crop next year! Thanks!
Crushed Egg Shells
If you grind your eggshells up you save from your chickens you can make your own diatomaceous earth for free!!!! (:
DE
A few weeks ago when I was inspecting my cabbages (green & red), broccoli, and Brussel sprouts, I noticed the green cabbages in particular looked like swiss cheese. I quickly bought (non food grade) DE and sprinkled it with a sifter from the dollar store. It works. It stopped the damage almost instantly. I've since decided to use only food grade so the local cats don't get sick even though I have most of my plants surrounded with chicken wire. When my fall lettuce starts growing I'll use it on this to as this summer I was plagued with cinch bugs. I'm so happy I saw the article on DE from the old Farmer's Almanac. Thanks to all.
DE non food grade
More a question than a comment. Does non food grade do any good against insects and why would it lose it's usefulness by getting wet? Does it loose it's silica or would it return to it's natural form when it dries? I am in Texas so I want to use it in the house as well as the garden.
The non-food grade is not
The non-food grade is not recommended because it has been subjected to high heat which changes its silica into crystalline silica which can be harmful to humans and pets. That is why it is only used for filters. Food grade is called amorphous silica. Since DE works by cutting thru the exoskeleton of an insect and drying it from the inside out it is not going to be as effective when wet. After it has dried out it will be effective again. It is recommended to reapply if it gets washed away.
DE
Caution, wonderful product, but have heard it is harmful to bees, so research safe usage more.
It is recommended that you
It is recommended that you not sprinkle DE on the blossoms of your plants to prevent bees from coming in contact with it.
De
I have used de for years with no issues to the bees. All of my animals eat it from the fish to the horses, people included, it have loads of benefits the list ia just too long to post here!