What Is Diatomaceous Earth?
Is it beneficial to use diatomaceous earth for succulents? Before answering that, what is diatomaceous earth? Diatomaceous earth (DE) is a soft naturally occurring sedimentary rock that was formed from fossilized hard-shelled micro algae called diatoms. It is easily crumbled into powder form of various densities. Depending on the source and the manufacturing process it is typically 80-90 percent silica along with iron oxide and alumina a clay mineral.
After it is mined it is ground into a chalk-like powder that is microscopically sharp-edged, coarse, hard and very absorbent.
For cactus and other succulents we recommend Harris Diatomaceous Earth.
Is it Beneficial to use Diatomaceous Earth for Succulents?
Regularly applying diatomaceous earth can be very beneficial to succulents. The primary reason is to keep your succulents free from harmful insects. There can also be another benefit. All succulents will become stresses if they are overwatered.
Succulents will also struggle if they are in a container or an outdoor area where the water does not drain well. In both of those instances the diatomaceous earth helps absorb the excess water allowing the soil to dry.
There is also some evidence that the absorbent properties of DE make it an excellent way to bind newly applied fertilizer. The fertilizer is then slowly released as the diatomaceous earth breaks down. This is perfect for succulents that can be harmed by fertilizer being absorbed into the roots too quickly.
Growing succulents hydroponically does not seem to be very popular but it can be done. The porosity of diatomaceous earth makes it a great medium to use in hydroponic containers.
How is Diatomaceous Earth Used?
Diatomaceous earth has hundreds of uses including pest control, toothpaste, metal polishes, filtration, liquid absorbent, thermal insulator, and as a filler in rubber and plastic products. Additionally, it is often sold in auto parts stores as an absorbent agent to soaks up and remove spilled oil.
Pest Control with Diatomaceous Earth
DE has become more and more popular as an insecticide. Diatomaceous earth is effective in killing or repelling a wide variety of insects including ants, fruit flies, ticks, wasps, bees, hornets, termites, aphids, silverfish, leafhoppers, earwigs, weevils, bed bugs, mites, crickets, cockroaches, maggots, beetles, scorpions, gnats, spiders and fleas. It is also very effective in detering slugs and snails in your outdoor garden. It is therefore an economical and safe pest control substance.
Diatomaceous earth is so effective at killing insects it is often mixed in with stored grains. The Bulletin of Insectology proved the efficacy of natural diatomaceous earth for killing grain beetles. Because of this there is a high probability that any grain based food product you purchase may actually include a trace amount of diatomaceous earth.
An important point is that diatomaceous earth will not kill worms or any of the beneficial microorganisms that are so good for your succulent soil.
Discourage Rodents and Other Animals from Ruining Your Garden
Diatomaceous earth will not kill animals but there is a way you can use it to keep them away. Many animals like rabbits, mice, moles and rats have a strong aversion to peppermint and citrus odors. Mix a few drops of peppermint or lemon essential oils into some diatomaceous earth and spread it around the areas you want to prevent the animals from visiting. The DE is highly absorbent, so it will retain the odor from the oils much longer than other methods such as cotton balls.
Is Diatomaceous Earth Safe for Pets and Children?
Numerous tests have proven that diatomaceous earth is harmless to animals and humans. In fact, some people purposely include diatomaceous earth in their diet. There are DE advocates that add it as a daily supplement because of its trace minerals and high silica content. Some people believe that ingesting up to ¼ cup a day will help with detoxifying, parasite control and colon cleansing. (This article will not be discussing taking DE orally since we are just focusing on using it for your succulents.)
Many farmers and ranchers actually mix diatomaceous earth into their livestock feed to prevent worms and control parasites. There are verified benefits for doing this and there is no evidence that it harms the animals in any way.
There are some anecdotal stories of people having problems after breathing in the diatomaceous earth “dust.” This has never been officially confirmed but just to be on the safe side it is best to be careful not to breath it in when using it.
Will diatomaceous earth harm wildlife? According to the National Pesticide Information Center, “Diatomaceous earth is practically non-toxic to fish and aquatic invertebrates. It is commonly encountered by birds and other wildlife, and it’s not known to be harmful.” [link: http://npic.orst.edu/factsheets/degen.html]
What Type of Diatomaceous Earth is Best for Succulents?
Always start with a food grade diatomaceous earth which is automatically a superior quality. This is what you should use for every application even if you are growing succulents that you do not intend to ingest. Diatomaceous earth that is not food grade quality may have many other additives that you simply do not want in your succulent soil. A label that states “98% diatomaceous earth” may have several unwanted additives that are harmful to your plants.
Caution: Never use diatomaceous earth that is sold as a pool cleaner. That is the lowest grade DE available and should not be used with your houseplants or in outdoor gardens. Pool grade DE is always heat-treated so it will intentionally crystallize. This calcination of the diatomaceous earth makes it no longer effective as an insecticide. Diatomaceous earth is so inexpensive there is no excuse for not using the best quality purest product you can find.
How Do I Apply Diatomaceous Earth to My Succulents?
You can generously apply DE to your outdoor succulents and the surrounding soil. When you need to apply it directly to the plants leaves and stems it helps to lightly spray them with water first. This will help more of the diatomaceous earth to cling to the plant. As soon as the DE has dried out it will become effective in killing your unwanted insects. If you are dealing with a serious pest problem, it will work better to regularly apply more DE.
For convenience some people prefer using a spray bottle to apply diatomaceous earth to plants. Simply add about one cup to a gallon of water and spray the solution on your succulents. After the solution dries out the DE will go to work killing any unwanted bugs.
It is usually not necessary but if there are already bugs on the foliage of the succulent itself you can just lightly dust the entire plant. Normally you only need to apply a thin layer of diatomaceous earth to the soil. It is best to do this soon after you have watered your plant but after the top surface of the soil has mostly dried out.
Remember that diatomaceous earth will not kill insect eggs of any kind. This means for indoor use you may need to vacuum up and then reapply the DE every few days for several weeks until you have killed all the adult bugs as well as their eggs.
When you purchase succulents from a nursery or any other store there is the possibility that gnats, blackflies, whiteflies or other bugs have already laid eggs in the soil. It may be days or weeks until the eggs start hatching and you discover you have a problem. A way to proactively prevent this problem is to re-pot your newly purchased plants as soon as you bring them home. Removing as much of the older soil as you can is the first step. There is no need to be so overly concerned that you end up damaging the roots while removing the soil. Just remove what you reasonably can.
If you are going to use the same pot that the succulent came in the next step is to wash it out with soap and hot water. Next, fill the pot with the new soil and plant your succulent. After watering your plant apply a light layer of diatomaceous earth on top of the soil. In a week or two after you water your plant apply a second layer of DE. This should be enough to be certain that there are no more living eggs in the soil.
Don’t hesitate to mix diatomaceous earth right into your succulent soil when you are planting or repotting a plant. The DE that ends up around the roots will improve air circulation and increase drainage. Regularly adding diatomaceous earth when planting or repotting your succulents will increase your success rate.
Will Diatomaceous Earth Effect the pH of My Soil?
All diatomaceous earth is alkaline and it usually has a pH level around 8. It is really not a great concern, however, since it breaks down so slowly it is unlikely to significantly change your soil’s pH level.
How Does Diatomaceous Earth Kill Insects?
There are some different opinions about the exact process that takes place when diatomaceous earth kills insects. One theory is that the microscopic particles stick to the exoskeleton joints of the insect. The particles are extremely sharp and essentially destroy the insect internally. Another explanation is that the microscopic particles that stick to the insect’s internal body parts simply depletes the bug’s necessary moisture causing dehydration which leads to death. It is also possible that it is a combination of both of those processes that actually kills the bug.
In any case, it is not a chemical poison per se that is killing the insects. It is a physical or mechanical method taking place. Because of this there is no way for insects to build up a tolerance as they do with man-made chemical poisons.
Will DE Kill Important Insects Like Bees?
In many parts of the world bee populations are in serious jeopardy and are in need of immediate protection. to as much help as we can give them. It is essential that we avoid anything that would harm bees since they are so vital for a healthy environment.
Thankfully bees are flying insects that do not crawl on the soil. For the DE to kill an insect it must first walk through it, so it clings to its body parts. Bees are very unlikely to come in contact with diatomaceous earth that is on the soil or a hard surface like concrete.
If you need to apply DE directly on outdoor plants and not just the ground, there are some precautions you should take.
Apply the DE in the late evening since the bees are less active and this will give the whole night for any residual dust to settle. This will prevent even the slightest chance that bees may fly through the dust and be contaminated.
There are some types of succulents where you may occasionally see bees typically crawling on the leaves and stems. Bees are particularly attracted to sedums and sempervivums. On these succulents avoid applying any diatomaceous earth to the foliage.
Never apply DE directly on buds or open flower blossoms so the bees will not accidentally come in contact with it.
What is the Best Diatomaceous Earth Brand?
There are many good brands of diatomaceous earth that will work well for your succulents both indoors and out. We have used many different brands over the years and we currently recommend Harris Diatomaceous Earth.
Harris Diatomaceous Earth
- Certified organic by OMRI.
- Food grade quality from a freshwater source.
- Does not contain any fillers or additives.
- Includes a free convenient easy-to-use duster.
- Comes in 2lb, 4lb and 10lb sizes.
Never use a household vacuum to clean up diatomaceous earth. It is better to use a shop vac or simply sweep it up. Diatomaceous earth is sold as such a fine powder that it has been known to damage conventional filtered vacuums.
Many experienced succulent growers use diatomaceous earth liberally for both indoor potted succulents as well as for their outdoor plants. We highly recommend diatomaceous earth for houseplants of all kinds including cactus and other succulents. There are no negative results from using DE. It is inexpensive and very effective at controlling harmful pests that can damage or even kill succulents. Diatomaceous earth helps more air to surround the roots which helps them remain healthy. Diatomaceous earth is perfect for succulents since it absorbs water but at the same time it quickly dries out.
Succulents are highly recommended for green roofs. Using diatomaceous earth as part of the growing medium on green roofs is a common practice. Horticulture Journal states, “Hardy succulents are the workhorses of extensive roofs and the primary plants for systems using a medium of 10, or less centimetres. [Succulent] Plants are native from dry locations, semi-dry locations, stony surfaces such as alpine environment. These kinds of plants have typical mechanisms to survive extreme conditions. Mechanisms like water storage organs, thick leaves, thick leaves surfaces, narrow leaves etc. They have unsurpassed ability to survive drought and wind conditions, store water in their leaves for extended periods and conserve water through a unique metabolic process. Hardly succulents like Sempervivum, Sedum, Talinum, Jovibarba, Delosperma are the only choices for thin substrate, non-irrigated, extensive green gardens with the greatest survivability… Generally, extensive green roof medium is a blend of sandy or granular materials that balances water absorption with adequate porous surface. A variety of natural and unnatural materials can be used to achieve balance. Lelite, pumice, diatomaceous earth, sand, expanded and active clays, expanded shale, gravel, bricks and tiles. And vermiculite or perlite can be used in conjunction with other materials.”