How to Use Diatomaceous Earth to Control Garden & Plant Pests

This organic powder is a powerful ally in your fight against arthropods in your garden & plants.

Published January 19, 2023
Gardener white sprinkle Diatomaceous earth

If you're looking for an organic way to control pests in your garden and/or home, diatomaceous earth (DE) is a good option. DE is a silica-based powder that's made from the fossilized remains of organisms called diatoms (hence the name). As with any pesticide, it's important to know how to use diatomaceous earth properly and to use it with care. Even though it's organic, using this product is not without risk.

What Is Diatomaceous Earth?

DE is not a poison - bugs don't have to eat it for it to work. It's a silica powder that has sharp, abrasive edges. When certain insects (arthropods) crawl over DE, its sharp edges cut through their exoskeletons, opening their insides to the air. This causes them to dehydrate and die. It can also act as a deterrent to soft-bodied garden pests, but it doesn't kill them.DE is organic, but it's still very important to use it with caution. Be sure to purchase DE labeled as garden safe or food grade when using it for outdoor pest control.

Need to Know

Wear gloves when working with DE to protect your hands from the crystals and to avoid skin irritation. You should also wear a mask to avoid breathing in DE, as doing so can cause respiratory issues. It will do the same thing to your lungs that it does to bugs.

How to Use Diatomaceous Earth in Your Garden

Applying DE can be a good way to kill arthropods (insects with exoskeletons) that infest your garden. Aphids, flea beetles, and spider mites are examples of arthropods that are common garden pests.

Need to Know

DE does not specifically target unwanted arthropods. It can kill all arthropods - including beneficial ones like ladybugs.

DE will also help keep soft-bodied insects like slugs away from your prized garden plants. Slugs don't like to crawl over the sharp edges of DE, so they'll usually turn around if they'll have to move through DE to get to a plant. I use DE for severe slug infestations, but only after trying other ways to get rid of garden slugs that aren't likely to harm any beneficial bugs.

You can apply DE to your garden in a few different ways.

  • Sprinkle around plants - Sprinkle a thin layer of DE powder around plants to form a barrier to help keep snails, slugs, and other crawling insects away from them. You can sprinkle from the package or use a DE applicator.
  • Apply to plant leaves - To deal with mites, aphids, or other leaf infestations, apply it directly to the leaves. You can use a DE applicator, a shaker bottle, or mix a tablespoon of diatomaceous earth powder in a liter of water in a spray bottle.

How to Use DE on Indoor Plants

When using DE indoors, be sure to purchase food grade DE (but don't eat it). You can use DE on houseplants the same way you apply it to the leaves of outdoor garden plants.

Important Tips for Using Diatomaceous Earth Effectively

DE doesn't work instantly. Sometimes it works in a few hours, but it can take several days. Don't assume it isn't working if you still see arthropod activity after applying it. When using DE, follow these tips for the best results.

  • Only use DE to combat arthropod infestations or to deter soft-bodied pests from getting to your plants. It will not work on other types of insects or pests.
  • If you're going to use DE indoors and out, get in the habit of only buying food grade so you don't have to keep track of multiple packages of the same type of product.
  • Don't forget that DE can irritate your skin and lungs. Wear gloves and a mask any time you are working with it.
  • Don't put DE in areas where pets may come in contact with it, as it can irritate their skin.
  • Even though you're using food grade DE, do not apply it to any kind of food or let it come in contact with food. If this happens, throw out the food.
  • Use DE to deal with an infestation rather than as a deterrent. There's too much risk to beneficial bugs to put it out when you are not actively trying to combat a problem.
  • It's best to apply DE outdoors when conditions are dry and the forecast doesn't include rain. It's ineffective when it's wet. Pouring rain will wash DE away from leaves or soil, so it won't be there after the rain.

Controlling Common Pests

Diatomaceous earth can be a good resource to inlcude in your efforts to control pests in your garden and indoor plants, but only certain kinds of pests. As with any form of pest control, it's important to read, understand, and follow the instructions on the package of DE that you purchase. Follow all safety precautions and use it to deal with garden or indoor pests when your goal is to eliminate an arthropod infestation or to deter soft-bodied insects from getting to your plants.

How to Use Diatomaceous Earth to Control Garden & Plant Pests