Can You Spray Diatomaceous Earth? A Comprehensive Guide

Yes, you can spray diatomaceous earth (DE), but the effectiveness depends heavily on the application method and the type of DE used. Specifically, food-grade diatomaceous earth can be mixed with water and sprayed, while pool-grade DE should never be sprayed. This article delves into the specifics of spraying DE, exploring its advantages, disadvantages, proper techniques, and crucial safety considerations.

Understanding Diatomaceous Earth

Before discussing spraying, it’s essential to understand what diatomaceous earth is. It’s a naturally occurring, soft, siliceous sedimentary rock that is easily crumbled into a fine white to off-white powder. This powder is composed of the fossilized remains of diatoms, a type of hard-shelled algae.

Types of Diatomaceous Earth

There are two main types of DE:

• Food-grade DE: This type is considered safe for human and animal consumption and is often used as an insecticide, dewormer, and food additive.
• Pool-grade (or Filter-grade) DE: This type is calcined (heat-treated) to alter its structure, making it more effective for filtration in swimming pools. This type is toxic if ingested or inhaled and should never be used for pest control around people or animals.

Spraying Diatomaceous Earth: The Basics

Spraying food-grade DE is a viable application method, particularly for reaching cracks, crevices, and plant foliage. The water acts as a carrier, allowing the DE to adhere to surfaces. However, it’s crucial to remember that DE is only effective when dry.

How to Prepare a Diatomaceous Earth Spray

1. Choose Food-Grade DE: Always start with food-grade DE.
2. Mix with Water: Use a ratio of approximately 4 tablespoons of DE per gallon of water. The exact ratio isn’t critical, but a milky consistency is generally ideal.
3. Agitate Thoroughly: DE doesn’t dissolve in water, so thorough agitation is essential. You’ll need to shake the sprayer frequently during application to prevent settling.
4. Use a Suitable Sprayer: A garden sprayer, hand sprayer, or even a pressure sprayer can be used. Ensure the nozzle is adjustable for a fine mist.
5. Strain if Necessary: If your sprayer clogs easily, you can strain the mixture through cheesecloth or a fine-mesh sieve.

Application Techniques

• Apply a Light Coating: Don’t saturate the surfaces. A thin, even layer is sufficient.
• Target Problem Areas: Focus on areas where pests are known to frequent, such as cracks, crevices, around baseboards, and on plant leaves (undersides especially).
• Reapply as Needed: DE loses its effectiveness when wet, so reapplication after rain or watering is necessary.

Advantages and Disadvantages of Spraying DE

Spraying DE offers several advantages, but it also has drawbacks that need to be considered.

Advantages

• Reaches Hidden Areas: Spraying allows you to reach areas that are difficult to dust directly, such as cracks and crevices.
• Easier Application on Plants: Spraying makes it easier to apply DE evenly on plant foliage, particularly the undersides of leaves.
• Reduced Dust Exposure: Spraying can minimize the amount of airborne dust compared to dry application.

Disadvantages

• Ineffective When Wet: DE is only effective when dry, so spraying requires reapplication after rain or watering.
• Settling: DE settles quickly in water, requiring constant agitation.
• Clogging: The abrasive nature of DE can clog sprayer nozzles.
• Lower Initial Efficacy: While spraying helps with adherence, the initial killing power might be slightly lower compared to dry application as the DE needs to dry first.

Safety Precautions When Spraying Diatomaceous Earth

While food-grade DE is generally considered safe, it’s still important to take precautions during application.

• Wear a Dust Mask: Even when spraying, some dust can become airborne. A dust mask will protect your lungs from irritation.
• Avoid Inhalation: Try to spray in well-ventilated areas.
• Protect Your Eyes: Wear safety glasses or goggles to prevent DE from getting into your eyes.
• Wash Your Hands: Wash your hands thoroughly after handling DE.

Frequently Asked Questions (FAQs) about Spraying Diatomaceous Earth

FAQ 1: Can I use pool-grade DE in a sprayer?

Absolutely not. Pool-grade DE is toxic if inhaled and should never be used for pest control purposes. Stick exclusively to food-grade DE for spraying applications.

FAQ 2: Will spraying DE kill pests immediately?

No, DE doesn’t work instantly. It kills insects by damaging their exoskeletons, causing them to dehydrate and die. This process typically takes several hours to a few days.

FAQ 3: How often should I reapply DE after spraying?

Reapply DE after it rains, after watering plants, or whenever you notice a decrease in effectiveness. A good rule of thumb is to reapply every 7-10 days in humid or wet environments.

FAQ 4: Can I spray DE on my pets directly?

While food-grade DE is generally considered safe for pets, direct spraying is not the best approach. It’s better to lightly dust your pet with dry DE, avoiding the eyes and nose. Always consult with your veterinarian before using DE on your pets.

FAQ 5: Is spraying DE more effective than applying it dry?

Neither method is inherently more effective. Spraying allows for better coverage in hard-to-reach areas, while dry application provides immediate contact with pests. The best method depends on the specific situation and pest being targeted.

FAQ 6: Can I mix DE with other pesticides in the sprayer?

Mixing DE with other pesticides is generally not recommended. It can alter the effectiveness of both substances and potentially create harmful reactions. Use DE as a standalone treatment.

FAQ 7: Will spraying DE harm beneficial insects?

Yes, DE is non-selective and can harm beneficial insects like bees and ladybugs if they come into contact with it. Avoid spraying flowering plants or areas frequented by pollinators.

FAQ 8: How long does DE remain effective after being sprayed?

DE remains effective as long as it stays dry. Once it gets wet, it loses its abrasive properties and no longer kills insects.

FAQ 9: Can I use DE spray indoors?

Yes, you can use DE spray indoors in targeted areas like cracks, crevices, and around baseboards. Just be mindful of dust exposure and ventilation.

FAQ 10: What is the best type of sprayer to use for DE?

A garden sprayer with an adjustable nozzle is a good option. A hand sprayer can also work well for smaller areas. Choose a sprayer that won’t clog easily and can produce a fine mist. Regularly clean your sprayer after use.

FAQ 11: Will DE stain my furniture or carpets?

DE is a white powder and can potentially stain dark-colored surfaces if applied too heavily. Test the spray on an inconspicuous area before applying it liberally. Vacuum up any excess DE after it has dried.

FAQ 12: Where can I buy food-grade diatomaceous earth?

Food-grade diatomaceous earth is widely available online and at garden centers, farm supply stores, and some health food stores. Ensure the product is specifically labeled as “food-grade.”