Diatomaceous Earth and Cannabis Growing [What Are the Benefits?]

Those unfamiliar with diatomaceous earth (DE) will likely wonder what’s so special about this sandy substance. However, once you learn more about it, you may decide to add it to your cannabis garden. Aside from its pest control properties, DE could condition the soil and help with nutrient absorption. Let’s learn more about this marvel.

What Is Diatomaceous Earth?

It is a naturally occurring siliceous sedimentary rock that resembles fine white powder. It consists of diatoms, the fossilized remains of tiny marine organisms. These hard-shelled algae sank to the bottom of large bodies of water over a 30-million-year period, resulting in a soft, powdery substance with an abrasive feel akin to pumice powder.

The substance remained unused and undiscovered until 1836 or 1837. A German peasant named Peter Kasten discovered DE in Luneburg Heath when sinking a well. The resulting extraction sites revealed deposits of up to 28 meters thick. Humankind has since found that DE has a myriad of practical uses.

There are two main types of diatomaceous earth:

  • Filter Grade: Though it is toxic to mammals, we use it to produce dynamite and for water filtration.
  • Food Grade: Its wide array of uses includes as an anti-caking agent and, crucially for cannabis growers, as an insecticide.

Should I Use It in My Marijuana Garden?

First and foremost, make sure you use freshwater DE for horticultural purposes. There is also a saltwater option that isn’t suitable for plants due to the high salinity level. The answer to the above question is ‘yes’ if you are interested in the following:

  • Organic pest control
  • Improved soil quality
  • Better nutrient absorption

Keep Pests at Bay Organically

One of the primary uses of DE in horticulture is as an organic pesticide. While it feels like a smooth powder to us, it is akin to acid for the types of pests that usually damage a cannabis garden. It is especially problematic for any insects with an exoskeleton. The list of pests that diatomaceous earth is lethal to includes:

  • Cockroaches
  • Ants
  • Aphids
  • Mites
  • Spiders
  • Earwigs
  • Slugs
  • Snails
  • Fungus gnats
  • Silverfish

Gardeners often use pesticides to deal with this threat, but they can remain in the cannabis buds. DE, on the other hand, is an all-natural method of dealing with a pest infestation. When you look at it beneath a microscope, you’ll notice that it looks like a pile of razors. These sharp edges cut through the protective covering of insects and suck out all of their moisture. Any insect unfortunate enough to consume DE will experience the above from the inside out.


Unlike chemical insecticides, insects don’t develop resistance to the effects of diatomaceous earth. Here are the three most common methods of application.


There is no ceremony involved here. Some gardeners dust their plants from top to bottom with DE. You should only use this method when the plants are not in the flowering phase.

Use a shaker or dusting canister to shake a layer of diatomaceous earth onto leaves covered in morning dew. If you plan to use DE in the afternoon or evening, spray the plants with water first. Next, shake off the excess liquid and dust with powder. Once the mixture dries, your plants are protected against pests.

Pesticide Spray

Create a solution that consists of four tablespoons of DE for every gallon of water. Shake the mixture and put on a mask before spraying to avoid inhaling particles. Spray the top and bottom of the marijuana leaves evenly. It is better to ensure the leaves are wet but not soaked. Again, it is best to use the spray while the plants are still in the vegetative stage.

If you use it in the flowering stage, your plants will absorb the spray, and you could consume it when smoking your cannabis. The diatomite activates and becomes active once the mixture dries.

Whether you spray or dust, make sure the layers remain thin. Too much DE could prevent the sun’s rays from penetrating the leaves, thus interfering with photosynthesis.

Soil Treatment

This method is best if your plants are in bloom and you want all-around protection. Apply the DE to soil that you don’t plan to disturb for several days. You can place the mixture across soil beds or in a ring around the base of plants. If there is heavy rainfall, you may need to reapply the powder.

If you spot a pest infestation, sprinkle an even layer of diatomaceous earth around the problem areas. It may take a couple of days, but you should notice a higher degree of control over the infestation.

What About Hydroponic Grows?

DE is available in small rocks rather than as a fine powder. It is suitable for hydroponically grown cannabis because it is absorbent, long-lasting, porous, pH neutral, and good for the environment. Apart from silica, it also contains essential minerals for plant growth.

Your plants will uptake the silicate and develop into robust and healthy crops with thick stem walls. One DE brand claims that its product resulted in a 25% increase in the production of pepper plants compared to clay pebbles.

When using it for cannabis, however, it is probably better to mix it 50/50 with clay pebbles if growing in big pots. This process will result in better aeration. Here are a few other benefits of DE products, such as ‘Diatomite’:

  • High silica content. The slow release of silica helps plants mature more quickly.
  • It is capable of absorbing 2.5 times its weight in water.
  • The granules are porous, so they provide excellent thermal insulation and aeration for the root zone of cannabis plants.
  • It is reusable. Once you are finished with it, wash it thoroughly, and then soak it in a solution of one tablespoon of bleach per gallon of water for 24 hours. The next step is to rinse the DE and ensure it is ready for another use.

Conditioning the Soil with DE

In general, the better the soil quality, the better the plant. The process of improving soil as a growing medium is called soil conditioning. DE works well in this regard by boosting the retention of moisture in the soil. It holds a large amount of liquid and dries at a much slower rate.

With DE, you improve soil quality, and benefit from more expansive root growth, not to mention denser and tastier weed with more resin.

There is also research into the use of DE as a silicon soil conditioner. Studies looked at how it impacted sweet potato and strawberry crops. Diatomaceous earth had the following benefits:

  • Increased strawberry root mass by 100%.
  • A 35% higher strawberry yield.
  • More flowers, fruit, and more prominent crowns.
  • A 47% increase in yield and gross margin in the sweet potato crop.

Better Nutrient Uptake

Another way to boost yield is to ensure your cannabis plants absorb as high a percentage of the nutrients you feed them as possible. When you add DE to your soil, it helps free up nutrients and ensure they become available to your crop as needed. The high silica content of DE gets absorbed into the plant tissue.

As a result, plants are more able to receive more nutrients when the powder activates. You ultimately benefit from higher yields and better stability with small pH fluctuations.

In simple terms, soil enhanced with diatomaceous earth can more readily exchange air and water. Air develops root systems, which lead to improved nutrient and water uptake. Plants grow best when they have a good air supply and proper moisture content, and DE can increase both.

Final Thoughts on Using Diatomaceous Earth in Your Cannabis Garden

DE in aggregate form is extremely versatile and is a worthy addition to any marijuana crop. In the main, gardeners like to use diatomaceous earth as a means of dealing with infestations without the use of pesticides or insecticides. You can sprinkle it directly on your plants or mix it with water or soil to protect your precious weed.

However, you should also consider using it to improve the overall quality of the soil. DE does an exceptional job of helping your plants retain nutrients. Research shows that DE aggregates show notable increases in water-holding capacity, improved filtration rates, and better air and water exchange. It could provide your crop with a higher yield, though you must use it carefully if your plants are already in the flowering stage.

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