If you are looking for a versatile mineral powder for your garden, Food Grade Diatomaceous Earth – Perma-Guard Fossil Shell Flour can be incorporated into a range of gardening, soil-management and household routines.
Also known as DE or fossil shell flour, diatomaceous earth is a naturally occurring material made from the fossilised remains of microscopic aquatic organisms called diatoms. These organisms developed silica-rich shells that accumulated over time, forming deposits that can be mined and milled into a fine powder.
However, not every form of diatomaceous earth is suitable for use around the garden. Understanding which grade to choose and how to apply it correctly will help you use the product more safely and effectively.
What Is Food-Grade Diatomaceous Earth
Food-grade diatomaceous earth is a finely milled mineral powder containing predominantly amorphous silica. Although it feels soft to the touch, its particles have a complex microscopic structure.
Perma-Guard Fossil Shell Flour is sourced from a freshwater deposit containing the diatom Melosira preicelanica. According to the manufacturer, this deposit contains approximately 89–95% amorphous silica, along with naturally occurring trace minerals.
Food-grade diatomaceous earth is different from the heat-treated material manufactured for swimming-pool filtration. Pool-grade diatomaceous earth has a different composition and must not be substituted for a product intended for garden or household applications.
Always check the product label and select a grade appropriate for your intended use.
How Does Diatomaceous Earth Work in the Garden?
Diatomaceous earth works physically rather than through a conventional chemical action. When certain crawling insects come into direct contact with dry DE, the powder can affect the protective waxy layer on their exoskeleton. This causes them to lose moisture and dehydrate.
Because direct contact is required, diatomaceous earth should be applied strategically in areas where unwanted crawling insects are active.
DE is most effective when it is dry. Rain, irrigation and heavy moisture can reduce its effectiveness or wash the powder away, which means outdoor applications may need to be repeated.
How to Apply Diatomaceous Earth Around Plants
Before applying any product, read and follow the directions provided on its packaging. The appropriate method and amount can vary depending on the area being treated.
For general garden applications:
- Choose a calm, dry day without rain in the immediate forecast.
- Make sure the plants and surrounding soil surface are dry.
- Apply a light, even layer to the targeted area.
- Concentrate on locations where crawling insects have been observed.
- Avoid covering flowers or areas regularly visited by bees and other pollinators.
- Check the treated area after rain or watering.
- Reapply when necessary and in accordance with the product directions.
A thick pile is generally unnecessary. A controlled, light application is easier to manage and less likely to create airborne dust.
Where Can It Be Applied?
Depending on the manufacturer’s directions, food-grade diatomaceous earth may be applied in targeted areas such as:
- Around the base of affected plants
- Along garden-bed edges
- In cracks and gaps where crawling insects hide
- Around pots and raised garden beds
- On dry soil surrounding vulnerable seedlings
- Around sheds, greenhouses and garden storage areas
Avoid scattering DE indiscriminately throughout the garden. Targeted application helps reduce unnecessary exposure for beneficial insects.
Using Diatomaceous Earth for Potted Plants
Food-grade diatomaceous earth may also be useful around potted plants where crawling insects are present.
Wait until the top of the potting mix is dry, then apply a light layer to the surface according to the product directions. The powder must be dry to perform its intended physical function, so its effectiveness will be reduced after top-watering.
If the potting mix becomes wet, allow it to dry before determining whether another application is required.
Does Diatomaceous Earth Still Work When Wet?
Diatomaceous earth is most effective for contact applications when it is dry.
Once wet, the particles cannot interact with crawling insects in the same way. The material may become effective again after it has completely dried, but rain or watering can also move it away from the intended treatment area.
For outdoor applications, check the area following:
- Rain
- Overhead watering
- Heavy dew
- Strong winds
- Soil disturbance
Reapply only when needed and according to the product instructions.
Protecting Bees, Worms and Beneficial Insects
Diatomaceous earth does not distinguish between unwanted insects and beneficial insects. Any susceptible insect that comes into direct contact with the dry powder may be affected.
DE (diatomaceous earth) does not harm worms in any way, whether the soil is wet or dry.
To help protect pollinators and other beneficial garden species:
- Do not apply DE directly to open flowers
- Avoid broadcast application across entire plants
- Treat only areas where unwanted insects are active
- Keep the powder away from bee nesting areas
- Avoid applying it while bees are actively foraging
- Use the smallest appropriate amount
Targeted use is generally preferable to applying the powder broadly throughout the garden.
Safety Precautions When Applying DE
Although food-grade diatomaceous earth is a naturally occurring material, it is still a very fine powder and should be handled carefully.
Avoid breathing airborne dust during application. Consider wearing appropriate respiratory protection, particularly when applying larger quantities or working in an enclosed area.
You should also:
- Avoid contact with your eyes
- Keep children and animals away during dusty applications
- Wash your hands after handling the product
- Store it securely in a cool, dry place
- Avoid applying it in windy conditions
- Follow all product-label precautions
“Food grade” describes the product’s grade and processing. It does not mean the powder should be inhaled or handled without sensible precautions.
Choosing the Right Diatomaceous Earth
When selecting diatomaceous earth for gardening, check that the product is clearly identified as food-grade and suitable for the intended application.
Perma-Guard Fossil Shell Flour is:
- Produced from a freshwater diatomaceous earth deposit
- Predominantly composed of amorphous silica
- A source of naturally occurring trace minerals
- Finely milled for versatile application
- Available for garden, household and animal-environment uses
Never substitute pool-grade or filtration-grade diatomaceous earth for food-grade DE. These are different materials intended for different applications.
Frequently Asked Questions
Is diatomaceous earth suitable for Australian gardens?
Food-grade diatomaceous earth can be used for appropriate applications in Australian gardens. Dry conditions generally suit its use, although it may require reapplication after rain, watering or strong wind.
Can I put diatomaceous earth directly on plants?
Application instructions vary. If the product directions permit plant application, use a light, targeted amount and avoid open flowers or areas visited by pollinators.
Does Diatomaceous Earth Harm Earthworms?
When applied lightly and selectively to dry soil surfaces, food-grade diatomaceous earth is unlikely to have a major effect on earthworms living deeper in moist soil. However, direct contact or mixing large quantities throughout the soil may harm beneficial worms. Avoid adding diatomaceous earth directly to worm farms or composting systems containing worms, and use targeted surface applications rather than spreading it throughout the entire garden.
How often should I reapply diatomaceous earth?
Inspect the treatment area after rain, watering or soil disturbance. Reapply only when the original layer has been washed away or is no longer positioned where it is needed.
Is food-grade diatomaceous earth the same as pool-grade DE?
No. Pool-grade diatomaceous earth is heat-treated for filtration applications and must not be used as a replacement for food-grade diatomaceous earth in gardens, homes or animal environments.
Should I wear a mask when using diatomaceous earth?
Because DE is a very fine powder, respiratory protection is advisable whenever dust could become airborne. Avoid inhaling the powder and follow the safety directions on the product packaging.
A Versatile Addition to Your Garden Supplies
Food-grade diatomaceous earth is a useful mineral product for gardeners seeking a targeted, non-conventional option for certain crawling-insect and garden-management applications.
The best results come from careful application: use it when conditions are dry, place it only where required, protect beneficial insects and reapply after weather or watering has displaced it.
Explore the available sizes of Perma-Guard Food Grade Diatomaceous Earth from Soil Solutions and always follow the manufacturer’s directions for your intended application.