Is Garden Vermiculite Dangerous? Vermiculite Pros and Cons

Vermiculite Pros and Cons - Is Garden Vermiculite Dangerous?

Over the past years, our gardening methods have greatly enhanced just to maximize food production that all of us could benefit from. We have developed various methods and other materials that we can use to improve our gardening journey.

In this article, we will tackle the material called “vermiculite” as one of the best aids for gardening.

We all know that when growing plants, it is essential that they must meet all the essential requirements such as soil, aeration, nutrition, and water. If you are having a problem with these aspects, it might be time to consider vermiculite to improve soil structure.


The Nature of Vermiculite

Pros and Cons of Garden Vermiculite

Practical Uses of Vermiculite

Plants to Grow using Garden Vermiculite; and

How to use Garden Vermiculite

What is Garden Vermiculite?

Vermiculite refers to the group of hydrated laminar minerals. It is processed through high heat that makes it expand into accordion-shaped pellets. They come in five different sizes starting from the smallest size, which is used in germinating seeds, and the largest size is used for soil improvement.

Moreover, other features of vermiculite are that they are free from rotting, deterioration, and molding. They are pretty durable and are odorless, non-toxic, and sterile. In general, vermiculite has a balanced 7.0 pH and is also lightweight with a higher compatibility rate with other mediums.

There are two types of vermiculites: crude and exfoliated.

The crude vermiculite, from its term, is the type of vermiculite that has not been heated or processed. It also comes in different grades, starting from large, medium, fine, superfine, and micron.

On the other hand, exfoliated vermiculite is the heated and processed vermiculites that are widely available in the market. They also come in five different grades, like the crude vermiculites. The difference, however, is that exfoliated vermiculite is based on weight rather than particle size which is the determining factor for crude vermiculites.

The primary purpose of vermiculite is to provide aid to the soil to improve its aeration and drainage so that nutrients can freely grow in the soil. This, in turn, is very beneficial for the growing plants as they can have all the nutrients they need, thereby resulting in production success.

Also, they are quite reliable for the starting seeds because vermiculite can fasten the seeds’ germination process.

They are responsible for absorbing calcium, magnesium, potassium, and ammonium, which is critical for young plants to thrive. Aside from that, they can also be mixed with potting soil so that your plants’ root systems will improve, allowing more space for nutrients to enter.

Furthermore, vermiculite is remarkably versatile as you can apply it in raised-beds, in-ground, and container gardening.

However, there are specific ratios to follow to maximize the benefits of vermiculite. Some of these benefits include eliminating packed down the soil, moisture control, proper root spread, and improves drainage.

In general, vermiculites are natural minerals that are mined and processed through extreme heat and formed into a lightweight granule. They are odorless and fireproof and are known to have several benefits in gardening.

Garden Vermiculite Pros and Cons

With all the relevant features of vermiculite, there are still some disadvantages when working with them. But before talking about its disadvantages, let us first discuss some of its notable advantages.

Pros of Garden Vermiculites:

It has a natural pH of 7.0, which is close to neutral, which means you do not have to apply other solutions to achieve a balanced pH.

Excellent water retention.
Longer days to dry out, leaving the root zone to stay wet for longer than usual.
It holds nutrients pretty well.
It can either be used alone or mixed with other growing media.
It is sterile, making it suitable for starting seeds.
Lower chances of root rot.
It is beneficial in terms of seed germination or plant propagation because the composition of vermiculites allows the plants to be pulled without damaging their roots.
It is durable and can be recycled because it does not decompose.

Cons of Garden Vermiculites:

Sometimes, it holds too much water for some plants.
It does not apply to all plants, especially those sensitive to longer days of wet environments.
Its water retention capacity may trigger the development of bacteria and fungus that thrives in a moist environment.
It is highly reactive to alkaline, which can raise the pH in the root zone damaging the plants.
It is a non-renewable resource, unlike coconut coir.
It isn’t easy to find in the local garden marketplace.
It is also relatively expensive, making it hard to use for small-scale farmers on a tight budget.

The most important part of working with garden vermiculites is to know the story behind the health-related issues associated with it. To do that, let us have a quick rundown on the history of vermiculites.

There is a mining company called Libby Mine located in Libby, Montana. They are known to be the biggest producer of vermiculites in the United States. The estimated production is roughly 70-80% of all vermiculites sold in the United States that came from Libby Mines for the past 70 years.

Later on, it was found out that vermiculites have naturally occurring asbestos minerals alongside them.

The Libby Amphibole asbestos contaminated the vermiculite, creating health and safety dangers, especially those that are used in construction works and attic insulation. This can also pose a threat to garden vermiculites as it can damage growing plants and farmers exposed to it.

Unfortunately, asbestos exposure is hazardous to human beings. When inhaled, asbestos fibers enter the lungs, which can cause serious illnesses such as lung cancer, mesothelioma, and other risky lung diseases.

On a positive note, the mine was closed in 1990. Several movements pioneered by the Environmental Protection Agency (EPA) have begun to investigate and mediate health issues caused by asbestos exposure. Nevertheless, the current production of vermiculite products is strictly regulated by The Vermiculite Association to ensure safety and avoid causing health problems.

To this day, garden vermiculites are already safe to use, thanks to the Environmental Protection Agency for making it happen. Growers can now enjoy farming when working with vermiculites.

Practical Uses of Garden Vermiculite

Garden vermiculite has many practical uses when it comes to gardening. But before that, let us consider the fact that not all soils are compatible with garden vermiculites.

The type of soil that is not suitable for vermiculites is clay soil. Adding vermiculite to clay soils can result in waterlogging and may reduce the aeration around the root system.

Also, some soil mixtures with airy components like coconut peat do not go well with vermiculites. This is because the soil’s ideal balance will be altered, making it an unhealthy place for plants to grow rapidly. Mixing garden vermiculites with this type of soil only cost you more without getting any in return.

Therefore, it is vital to know the type of soil to pair with garden vermiculites. You can choose almost any type of soil except for clay soil and soil mixed with coconut peat.

To know more about garden vermiculites, here are some practical uses of it:

Mixed it with other growing mediums. Adding vermiculites to amend the soil for conditioning or putting it with compost creates a healthy environment for the growing plants to accelerate growth.

Use Garden Vermiculites as a growing medium alone. They are suitable for starting seeds because they promote seed germination. Also, they help to start seeds to absorb critical nutrients like magnesium, ammonium, potassium, and calcium.

Garden vermiculite can sustain growth in hot climates because of its water retention. Gardeners do not have to water their growing beds frequently if it is mixed with garden vermiculite.

Since the different sizes of Garden Vermiculites allow it to become versatile, you can use the medium-grade vermiculite for root cuttings. Just water it properly and cut the roots up to the node.

Suppose you are using garden vermiculites alone for starting seeds. In that case, you need to feed the seedlings a weak fertilizer solution of 1 tablespoon of soluble fertilizer per 4 liters of water after the leaves appear. However, if you mixed it with soil or peat, there is no need to supply fertilizer because it can already sustain fast seed germination.

Garden vermiculites eliminate packed-down soil, allowing more space for excellent aeration, limiting watering periods, and root spreading. A packed down soil is so dense that it makes no room for aeration and root spread, but if you mixed garden vermiculites with it, you would achieve an excellent growing medium.

Garden vermiculites are also suitable for transplanting. You have to dig a 6 inches hole enough to fit the roots without getting pressed, filling in the vermiculite, and removing topsoil.

Garden vermiculites can regulate drainage systems. When working with root crops, please put them in a container and pour the vermiculite around them. The garden vermiculites will absorb the excess water to prevent rot while protecting them from temperature alterations.

Lastly, aside from its suitability for growing plants, garden vermiculites can also be used for flower arrangement. You just have to water the vermiculite to saturate it entirely without any excess and place the flower in it. You do not have to water it daily because the water retained in the vermiculites is enough to sustain the flower.

Plants to Grow in Garden Vermiculite

To know more about the capacity of vermiculites, it is vital to determine the type of plants to grow in them. This is to ensure that you will have a memorable farming journey free from any faults or mistakes.

However, it is noteworthy that the plants mentioned below will depend upon the capacity of the growers. They don’t need to grow all these plants because they are using garden vermiculites. Garden vermiculites only provide comfort to the growers by helping them accelerate the growth rate of the plants that each grower loves to grow.

Below are the examples of herbs, plants, and root crops that love to grow in moist soils.

Herbs that prefer and thrive in moist soils:

Bee balm
Marsh Mallow
Sweet Joe Pye
Chameleon plant

Plants that prefer and thrive in moist soils:

Spider plant
Lucky Bamboo
Himalayan Honeysuckle
False goatsbeard
Siberian Flag Iris
Bleeding heart
Candelabra Primula

Root crops that prefer and thrive in moist soil:

Skirret Carrot
Tanier Spinach

Steps on How to use Garden Vermiculite

For the last part, we will discuss how to work with garden vermiculite properly. This is very crucial since not all growers know how to handle garden vermiculites. So, for the starters, here’s what you should do:

Prepare the growing container.

If you are growing indoors, it is expected that you will use containers. You mixed the potting soil with enough garden vermiculite to ensure that the soil is at the correct level before planting anything. The right mixture of soil and vermiculite is also applicable in raised-bed and in-ground gardening.

Prepare the garden vermiculite.

To prepare the garden vermiculite, you have to take the bag of the vermiculite and open it on the top. Take a rough estimate of 25% of the vermiculite to be mixed with the soil. This is the recommended amount of vermiculite enough to promote ideal soil conditions for rapid growth.

Now, scoop the 25% estimate of vermiculite out of the bag and put it in a container. The next thing you need to do is pour the soil on top of the vermiculite. After that, you have to work your way using your bare hand by mixing the soil and vermiculites while keeping a record of the two’s exact distribution.

Spread the garden vermiculite

This method is appropriate if you are growing in a small container, especially indoor farming. To do this, you need to put enough garden vermiculite in the small container and spread them evenly using your bare hands until it is completely mixed with the soil. Take note that you should add garden vermiculite before planting anything; otherwise, you will damage the roots.

Another method, if spreading and mixing with your bare hands does not work for you, is by putting the two substrates—soil and vermiculites—in a small plastic bag. Shake the plastic bag until the two substrates are fully integrated. Put the mixture in a pot or container of your choice and start planting or sowing your seeds.

Transplanting and seed preparation

When transplanting, make sure to remove all the excess soil in the roots from the old soil before replanting them.

In doing so, be very delicate enough to prevent damaging the roots; otherwise, the plants will have a slower growth rate, and sometimes they may not survive due to the shock of transplant if the roots are damaged.

After the transplant, sprinkle some garden vermiculite on the plant’s base for some additional water retention.

For seed preparation, make sure to read the seed packet’s directions to know about the recommended planting depth.

This is because seeds have different needs; hence it is vital to check their requirements. After sowing the seeds, you can cover them with a thin layer of vermiculites to promote seed germination and avoid weeds’ growth.

Water the container

Of course, water is an essential element for growing plants, or else they will die. The addition of vermiculite in the growing medium only promotes moist retention to ensure that plants have enough supply of water without watering them frequently.

Also, when working with vermiculites, gardeners should be careful that they should not overwater the containers. Remember that the garden vermiculites have great water retention and overwatering them may result in root rotting.

Remove excess water

When you accidentally overwater the container, do not panic and just remove the excess water. If you have smaller containers, just turn them upside down to drain the water. If you have bigger containers, tilt it on its side and let the water run down.


In the end, working with garden vermiculites is proven to be helpful for growers. Although it has a long scary history, it never became the reason to hinder the benefits it can give to the growers. All thanks to the Environmental Protection Agency (EPA) for their persistent efforts to ensure that every vermiculite is safe to use.

Garden vermiculites have some notable advantages that far outweigh their disadvantages.

Growers can now enjoy farming with the help of garden vermiculites. Also, by using garden vermiculites, they have more options of what type of plants to grow.

If you are a grower, it is never a mistake to expand your arsenal and gardening skills. You should consider the things to observe when working with garden vermiculites, including its cost.

If you can afford garden vermiculite, go and try using it in your garden, but ensure that you avoid clay soils and soil mixed with coconut peat.

Jenny M
Tribal Writer

Edited by
Patricia Godwin

Patricia Godwin

Patricia has many years of experience as a content writer on various subjects, but her first love is gardening. She’s never met a plant she didn’t like and, consequently, she writes about every type of plant you can think of. Once an avid gardener with a herb garden, a succulent rockery, and a rose garden – to mention a few. Nowadays, she’s constantly on the move searching for interesting plants to bring to your attention; and explain to you all the details you need to grow, care and maintain these plants.

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