Perlite Vs Vermiculite: Differences – Which One Is Better?


perlite vs vermiculite

Perlite Vs Vermiculite

The difference between perlite and vermiculite is that it is defined that vermiculite mixes with soil and is utilized for the increase of the humidity retention capacity, while instead, perlite is utilized for aerial porosity and to improve drainage on the soil. Thus, in the perlite vs vermiculite discussion, whereas perlite is adequate for cuttings and splitting, vermiculite is recommended for seedlings.

Analyzing perlite vs vermiculite, we define that they have two different purposes. Vermiculite may cause the root to rot in plants that like the soil to dry before being watered again. Instead, perlite does not retain water in the soil for plants like lettuce and broccoli that prefer constant water. Furthermore, the soil temperature will rise faster also, causing them to bolt earlier in the season. Vermiculite adds potassium and magnesium to the soil while perlite contributes nothing.

Perlite, unlike vermiculite, does not contain any nutrients. It is not able to participate in ion metabolism. If we have the experience of landless cultivation of Senpolia (a mixture of peat, perlite and vermiculite is commonly used in the USA), the absence of reactions of perlite does not affect the feeding program. The success of this method lies in special fertilizers and wick irrigation.

Vermiculite has in its composition such macro elements as calcium, potassium magnesium, iron, silicon and aluminium. However, these elements are in a bound state. The ability to bind elements enables the gradual release of substances present in the soil, which improves its structure. No wonder vermiculite is called an “agronomic” breed.

Vermiculite can absorb and gradually release moisture, while pearlite is not moisture resistant in its properties. Vermiculite absorbs 400-500 times more than its own mass and gradually releases moisture. It is therefore recommended to reduce watering when vermiculite is present in the soil, and for succulents it is better to add perlite to the soil mixture.

Perlite and vermiculite are inorganic soil conditioners. Their main advantage is that they are now very easy to buy in any garden centre. And that is why with their help you can quickly improve your affairs, i.e. quickly improve the performance of soil intended for transplanting plants or sowing seedlings.

Among many modern fertilizers, perlite and vermiculite are not the last to be used in indoor flower growing. Until recently, few people knew that these materials could be used for these purposes, but today you can safely buy them in any flower shop. Despite the fact that perlite and vermiculite are very similar for plants, there is still a difference, and now we will find out which one. Vermiculite and perlite are increasingly used in horticulture.

Especially in seed, cutting and propagation farms vermiculite and perlite are increasingly being introduced into the soil and potting soils to ensure a better and more airy structure.

Since vermiculite acts like a sponge and absorbs more water than perlite, it doesn’t aerate the soil as well. This means less oxygen for plant roots. If you use it when growing plants that don’t need damp soil, you might find your plants suffering from root rot. So be aware of your plants’ needs when you decide how water retentive you want your soil to be.

There are major differences between vermiculite and perlite, making it important to choose the right one, lest your garden be ruined by a bad growing media choice.We’ve already covered the biggest difference: Vermiculite will mix with soil and help to retain water. Perlite, on the other hand, will add drainage to the soil that it’s mixed with

Vermiculite finds its way into many seed starting systems. It both protects seedlings from fungus that so often ruins seed starting, and helps to retain water in the tiny little pods that seeds start in. While perlite can be used with seedlings, it’s better used when you move your seedlings into separate pots for additional drainage.

Perlite Vs Vermiculite: The difference between perlite and vermiculite

  • Moisture content

Vermiculite acts like a sponge, it can absorb five times its own weight in moisture. In this case the material keeps the moisture near the roots and the nutrients in the soil. If you use it, the time between waterings will increase.

Perlite has harder particles, absorbs less water, but loosens the soil more efficiently and improves aeration and drainage. Prevents an earthen coma from drowning out and distributes moisture more evenly.

  • Chemical properties

Vermiculite is involved in ion exchange, absorbs mineral substances and passes them on to the plant when needed, thus avoiding “overfeeding”. In a neutral environment it can, in interaction with hard water, change the acidity of the soil to an alkaline environment. Maintains the heat balance and gas exchange.

Perlite does not undergo chemical and ionic reactions. Therefore it is a sterile medium for growing seeds, seedlings or root cuttings. It is great for hydroponics. Protective equipment is required when working with it, as fine glass dust enters the human body through inhalation and is not removed by the body. Often these two inorganic substances are used together to maximize their positive soil properties.

Both materials have an extensive list of positive properties, which makes them an excellent option for improving the substrate. However, each gardener decides for himself what type of material to use, taking into account the tasks that need to be tackled. Now that you know the difference between pearlite and vermiculite, it will be easier for you to make a choice.

In recent decades, new thermal insulation materials have been used in individual buildings: perlite and vermiculite. Their properties have many commonalities, and developers often ask themselves what type of insulation they prefer, what option they choose to increase thermal and sound insulation while saving financial costs.

What Is Perlite?

Before we continue with the comparison of perlite and vermiculite, let us consider each of the materials separately. Perlite is a rock of volcanic origin and is considered a very useful mineral. When the lava comes into contact with the earth’s surface, or more precisely immediately after it has cooled, a mineral called obsidian is formed, which is later hydrated by groundwater.

The obsidian hydroxide obtained is perlite. This material is most commonly used in the construction industry, where it is used for sound and heat insulation and to reduce the risk of fire. Perlite is often heat treated in special furnaces before direct use, where it swells under the influence of high temperatures (such as popcorn). As a result we obtain Agroperlite in the form of a homogeneous bulk material. In agriculture it is most often used for mulching the soil, but in indoor flower growing it has proved to be an excellent alternative to the use of sand.

Unlike vermiculite, perlite is an inorganic rock that expands into a porous, airy and light grain after heating. It is often used as an additive in potting soils, cuttings, seedbeds and cuttings. As an additive in potting soils, perlite ensures a lighter substrate and better drainage of water, making it particularly suitable for plants that must not stand on damp soil, such as poinsettias. Perlite is also available in various grain sizes:

  • Pearlite 1: 0-1.0 mm. Generally not used in horticulture.
  • Pearlite 2: 0-3.0 mm. Used for sowing and cutting soil, as a pure substrate and in some cases as a light reflector in carnations and lathyrus.
  • Pearlite 3: 0-6,5 mm. For mixing with potting soil for a lighter structure.

Perlite is also available in substrate mats which can be used as substrate in various crops under glass. As perlite is easily steamable, the substrate mats can be used for several years. Both vermiculite and perlite consist of rock and are therefore not biodegradable.

Experts therefore recommend using only coarse-grained material in flower growing, although it is rather difficult to find for inhabitants of urban megacities. Perlite is a natural alternative to sand, as it is a chemically inert and not moisture-resistant material, which means that its main function is to loosen the soil, but nothing more. If you use this material, you will no longer have the problem of crust formation in the upper part of the soil, which often occurs when the soil cakes together (simply sprinkle perlite on the surface of the soil).

The snow white granular particles of perlite are a form of volcanic glass. Each particle contains about 6% water. When they get heated quickly to 1800°F they become porous.

Perlite is a mineral (foam glass) with a sterile environment, is an inert, highly effective loosening additive for the soil, low in chemical nutrients and completely free of organic substances. Originally used as a substitute for sand, which is difficult to find in the city.
The particle size of perlite can be 1 to 5 mm, agroperlite includes fractions of 2.3 to 5 mm. Smaller particles (perlite sand) have a high bulk density and are less air-intensive, while larger ones are fragile.
The most important properties of perlite are the loosening of the soil and the improvement of its structure. Perlite is able to store 3-4 times its own weight in moisture and has excellent heat protection properties. The optimum composition of the mixture is obtained by adding 15-35% Agroperlite. A large fraction can be used as drainage by pouring up to 5 cm of wet Agroperlite onto the bottom of the pot. A great advantage of Agroperlite is that it does not crumble or cake. The advantages of perlite also include complete sterility: no special disinfection is required before use.


Perlite particles are very light and therefore very popular in container gardening. It is also actively used for the greening of house roofs, where light substrates must be used to minimise roof loading.
However, allergies to perlite should be treated very carefully: In dry condition it is very dusty. In order to remove perlite dust, some gardeners moisten or rinse before use. A large amount of perlite dust makes the soil dense, breathable and therefore unsuitable for the development of the root system of plants.

At the edge of the lava flow, volcanic glass obsidian is formed at places where magmatic melts and the earth’s surface primarily come into contact, as a result of the rapid cooling (quenching) of the lava. Subsequently the groundwater penetrates obsidian, its hydration and the formation of obsidian hydroxide – perlite.

The water in the original perlite is present in two main forms: free (on the surface of the rock) and bound. The presence of constitutional water gives perlite the ability to swell when heated. Water reduces the softening point of the rock and acts as an expansion agent when molten. Pearlite is expanded in furnaces by thermal shock at 900 to 1100 ° C.

In this case, pearlite changes to a pyroplastic state. The development of gases, mainly H2O, is explosive and the glass foams to form expanded perlite with high viscosity. Bound water, which evaporates, creates countless small bubbles in a softened mass. The rock disintegrates into spherical grains with a 4 to 20-fold increase in volume and a porosity of up to 70 to 90%.

Pearlite is sand or gravel in appearance (depending on the degree of pregrinding), colour from snow white to greyish white, odourless. Perlite is refractory, has thermal and acoustic insulation properties and high absorbency (up to 400% of its own weight). Perlite is able to absorb water intensively at first and then gradually release it to the roots of plants and other perlite particles.

Due to this ability, after drying, perlite, which is located in the upper layers of the soil, draws water from the lower layers and supplies the roots of plants with moisture. Due to the even distribution of moisture in the soil, the temperature in the root area is well averaged. It is known that the thermal conductivity of the soil is directly dependent on density. The lower the density, the worse the energy moves through such a medium: the soil cools down more slowly and warms up more slowly.

This protects the roots from both freezing and overheating. Perlite is not subject to decomposition and decomposition under the influence of microorganisms, is not a favourable environment for insects and rodents. Chemically inert: neutral to alkalis and weak acids.

What should be done before applying perlite?

As everyone has already understood, the main preparation of perlite for use is washing. When dry, perlite is very dusty and its dust is not completely harmless. After inhalation, nose and throat may scratch for a long time. Therefore, before washing perlite, turn on hot water in the bathroom for 5-10 minutes. The resulting moisture will “beat” the perlite dust, which will fly safely when the bag is opened. Some gardeners recommend cutting a small hole in the bag and spraying it with water from the gun. Then you can pour the perlite into a gauze bag (the gauze must be folded in 2-3 layers) or pour it into a flour sieve and rinse it quietly.
Never put your nose in the bag and watch out for dust.

Perlite has a neutral pH, contains no seeds, insects or diseases. Tiny cavities on the surface of the perlite hold plant nutrients and moisture (3-4 times is weight), the space between them creates drainage and aeration.

Advantages: Better at draining, helps plant roots breathe, better for hydroponics, lightweight substitute for sand.

Disadvantages: lightweight and can float to the top of the soil, may create breathing problems for those susceptible, more expensive than vermiculite.

What is vermiculite?

This is a sheet material of golden brown or silver colour, in fact it is Hydromica. The name itself comes from the Latin word vermiculus, which means “worm”. When vermiculite is heated, its plates become thread-like grains, similar to “worms”. The porous structure of this material acts like a sponge, absorbing and storing moisture whose volume exceeds 4 times its own weight. Because of this property, vermiculite is simply an indispensable additive to earth mixtures, it keeps the soil moisture for a long time (closer to the roots), all its useful substances.

Vermiculitis – what is that? It is a chemically inert mineral that contains no toxic substances, heavy metals. This material is environmentally friendly, does not decompose, does not decompose, is neutral to acids and alkalis. It contains valuable components that positively influence the growth and development of green plants – calcium, magnesium, silicon, potassium, aluminium, iron. The components of vermiculite are partially absorbed by the plant as needed, but do not act as a main fertilizer (chemically inert). The material improves soil aeration, can change the pH (alkaline) and maintain soil moisture, which prolongs the time between watering.

Vermiculite is a mineral (rock) that expands when heated as a harmonica. This results in a very light grain with high water and moisture content. Because of this property, vermiculite is often used in horticulture as (additive to) substrate on seed, cut and propagation plants. This ability to retain water and moisture ensures that, on the one hand, irrigation water is retained and therefore nutrients are washed out much less quickly, and on the other hand, the soil structure remains airy and rich in oxygen, which makes it easy for plants to form roots. In addition, vermiculite is often used as a gritting agent for germinating seeds or as a medium for bulbs.

Vermiculite is available in various grain sizes:

  • Vermiculite 1: 0-1.5 mm.
  • Vermiculite 2: 0-3 mm. This is used for scattering flower seeds to promote seed germination.
  • Vermiculite 3: 0-5 mm. This is used for scattering vegetable seeds and for mixing into potting soil.
  • Vermiculite 4: 0-10 mm. This is used for spreading the bulb during packaging.

Vermiculite for plants – how do I apply it? The most common material used in the cultivation of plants is Agroermiculite, which is processed in a special way (combustion) and was developed especially for floriculture and horticulture.

It can hold potassium, magnesium, calcium and ammonium that feed and support young growing plants. It mixes well with soil.

Advantages: retains more water than perlite, contains trace minerals, less expensive.
Disadvantages: not as durable as perlite.

The use of perlite and vermiculite in floriculture

  • Perlite and vermiculite are used as drainage layer. Larger fractions are suitable for this.
  • Both substances are used to germinate seeds or to root cuttings. Usually in the same mixture with peat or sand. The substrate is pre-moistened.
  • The soil surface is sprinkled with perlite or vermiculite to prevent crust and mould formation.
  • The pH environment of these substances is almost neutral. This should be taken into account when plants whose growth requires an acid environment (azaleas and gardenias) are added to the soil.
  • Use for storing light bulbs. Due to the heat-insulating properties of these substances, the bulbs are well stored in winter and do not rot.
  • Application in hydroponics. A mixture of perlite and vermiculite is often used. The first one conducts water very well, but keeps moisture poorly. And the second, on the contrary, retains the moisture but becomes denser and hinders the access of oxygen. Together they complement each other.

Origin and production of bulk materials

Both materials are of natural volcanic origin: perlite was formed by hydration of volcanic glass, vermiculite is a mineral from the Hydromica group. Expanded materials are used in the construction industry. For this purpose the gravel perlite is heated in special ovens to a temperature of 1000 degrees. During heating, the complex water is converted into steam, which reduces the bulk density of the material. The result is bulk perlite, the fine parts of which are used in the construction industry. Perlite is lamellar and in the form of spherical grains.

A similar expansion method is used with vermiculite. After processing by accelerated firing, the porous material takes on a volume of flake particles increased by a factor of 15-20 and varies in fractional composition, bulk density and thermal insulation properties.

Perlite or vermiculite: which is better?

There is no definite answer, as the physical and technical properties are similar and determine the many possibilities of using both types of material in construction and other fields. In their pure form they are not used after grinding and heating at high temperatures, but only in their expanded form.

Expanded perlite and vermiculite are loose porous substances of different fractions that have identical properties but are of different natural origin. They have similar properties, which are characterized by:

  • excellent thermal insulation performance;
  • high fire resistance;
  • environmentally friendly;
  • inertia towards organic and chemical substances;
  • resisted decay and decay;
  • significant water absorption.

Vermiculite is characterized by a higher elasticity than perlite, whose structure changes into small particles upon physical exposure, making it very dusty. When inhaled, dusty particles settle in the lungs. When working with pearlite, it is therefore essential to use protective equipment.

A serious difference between perlite and vermiculite is the mechanical strength. Thermal insulating panels are made on the basis of expanded natural materials and the strength factor influences their properties. Perlite is very fragile and often breaks down during transport. It is therefore recommended that when transporting perlite cement boards for house insulation, the packaging should be laid and fixed with special films.

Be vigilant and practical! Bulk perlite should be purchased in the package. If you order the delivery of material in bulk, you will receive half of the volume when transporting in an open machine, as the second wind blows on the way.

Expanded perlite and vermiculite are also used:

  • as a component of masonry mortar to prevent cold bridges in the walls;
  • by using it as an additive in warm, decorative and fireproof plasters, the thickness of the insulation can be considerably reduced.

Perlite and vermiculite are good fillers for lightweight concrete, competing with each other and with the expanded clay used for these purposes.

(fr. Perlite) – Rock formation. When magmatic alloys come into contact with the earth’s surface, a sharp drop in temperature creates obsidian. Afterwards its hydration (addition of water molecules) and the formation of obsidian hydroxide, directly perlite (fr. pearl – pearls). Pearlite is available in black, brown, green and other colours. After heat treatment, perlite is crushed and transforms into a homogeneous white mass. Its properties are identical to those of sand, at the same time it is more porous and lighter and does not contain any impurities. It is most commonly used as a filler for mixtures.

Hydromica, which is produced by hydrolysis and weathering. Vermiculite is a golden brown mineral plate. When the plates are heated, you will see worm-like scales (lat. Vermiculus – worm) of golden or silver colour. Agrovermiculite is a vermiculite that is thermally processed in an oven.

FLOWER APPLICATION

  1. Perlite and vermiculite are used as drainage layers. Larger fractions are suitable for this purpose.
  2. Both substances are used to germinate seeds or to root cuttings. Usually in the same mixture with peat or sand. The substrate is pre-moistened.
  3. The soil surface is sprinkled with perlite or vermiculite to prevent crust and mould formation.
  4. The pH environment of these substances is almost neutral. This should be taken into account when plants whose growth requires an acid environment (azaleas and gardenias) are added to the soil.
  5. Use to store light bulbs. Due to the heat-insulating properties of these substances, the onions are well stored in winter and do not rot.
  6. Use in hydroponics. A mixture of perlite and vermiculite is often used. The first conducts water very well, but does not retain moisture well. And the second, on the contrary, retains the moisture, but becomes denser and hinders the access of oxygen. Together they complement each other.

Vermiculite

Vermiculite – a mineral from the Hydromica group, externally it is an expanded mica. From a chemical point of view it is “hydrate of magnesium-ammonium-aluminium-iron and silicon”. Vermiculite is divided into groups according to the size of the fractions (1, 2, 3, 4, 5 – i.e. from the largest to the smallest). Fractions 2, 3 and 4 are used for floriculture, but a larger fraction is also suitable for large farms and landscaping work.
For planting house plants and seedlings, fine- and medium-fraction vermiculite is added to the soil, the addition of which improves the soil structure. In particular, the breathability and water retention capacity of the soil is increased. For this reason it is even called “agronomic” rock.


Vermiculite is a very light material in its dry form, its porous granules have a high moisture capacity. They are able to quickly absorb a large amount of water (per 100 g of their own weight they absorb 400-530 ml of water), but due to their low hygroscopicity they do not absorb moisture from the environment (at 100% humidity, vermiculite moisture is about 10%).
Another remarkable property of vermiculite is that it is itself a source of useful minerals such as potassium and magnesium, which are easily absorbed by plants. In addition, vermiculite can retain nutrients that are introduced into the substrate during fertilization. However, it does not bind them forever, but gradually returns them, thus prolonging the flow of nutrients and water to the roots of the plant.
It should be noted that vermiculite is not only actively used as a soil additive: It is used to press it into heat and fire retardant materials, which are used as a component of fire retardant coatings and as a heat and sound insulating filler.

To what extent are Perlite and Vermiculite similar and different from each other?

Perlite and vermiculite are similar and at the same time different from each other.
– Vermiculite is a specially prepared mica, a mineral with a leaf structure, and Perlite is a foamed volcanic glass.
– Vermiculite, unlike perlite, is not dusting. At the same time, many experienced flower growers advise washing it before use, but not too long, rinsing too long will destroy the vermiculite sheets. You can sieve vermiculite through a flour sieve without rinsing it.
– Perlite is inert from a nutritional point of view (all the substances it contains are bound, not digestible by plants), but vermiculite contains potassium and magnesium in accessible forms.
– The colour of perlite is white, which determines the good reflectivity of the material, i.e. perlite in the upper layer of the substrate can easily reflect light to the underside of the leaves (as if the plants were additionally highlighted from below). Vermiculite has a silver or golden colour, its reflectivity is lower.
– Because of the presence of both components in the soil, the substrate cannot overheat in hot weather, but in cold weather it protects against overcooling.
– Perlite is very popular for use in hydroponics due to its inertness. Here it is used both in its pure form and mixed with vermiculite.
– Both are often used for rooting cuttings and germination of seeds.

– Both are not subject to decomposition and decomposition: their use reduces the risk of pests and the development of mould, which is particularly important for seedlings. They can also be used for winter storage of onions and tubers.
– Both are used as a drainage layer, for which large fractions are suitable. It is poured onto the ground at a height of 5 cm and can be mixed with expanded clay.
– Like perlite, vermiculite is almost neutral, so adding it to the soil mixture can reduce the acidity (use together with peat).
– Vermiculite and perlite can theoretically be reused (vermiculite after calcination, perlite after steaming), but it is not realistic in practice because it is very difficult to separate them from the soil at home.

When should perlite be used in combination with vermiculite?

Perlite and vermiculite complement each other perfectly: Perlite conducts water well but does not retain moisture well. Vermiculite, on the other hand, stores moisture, but becomes denser and hinders the entry of oxygen. Together – this is an ideal composition for improving the soil.
They are added to the soil at 15% each, so that the substrate is present at 30% in total. Growing plants in a mixture of pure peat, perlite and vermiculite is ubiquitous among gardeners. In this case, the lack of nutrients helps to clearly calculate the required fertilizer doses and the time of their application.

However, do not add much vermiculite to substrates for cacti and succulents, for these drought resistant plants it is better to use perlite as a loosening component.

Based on our passion for violets, we find tips for making a looser substrate by adding various baking powders. The most important are vermiculite and perlite. But what is it and which is better? Let’s take a closer look at them and describe them in comparison.

Conclusions

Perlite and vermiculite materials of different origins have a common purpose: to make the substrate looser and more breathable.

1. The advantage of perlite is a more even distribution of moisture in the earthen coma, it dries faster between irrigations and can therefore be used for wicking. Vermiculite, on the other hand, is well suited for traditional irrigation as you can extend the time between waterings.

2. Furthermore, perlite has a positive electrical charge and therefore cannot absorb positive fertiliser ions that are not involved in the ion exchange process.

3. In the composition of perlite all substances are in a bound state and inaccessible to plants. At this stage vermiculite contains potassium and magnesium in an accessible form.

4. Vermiculite has a more elastic structure, which offers advantages over perlite, where the structure is destroyed by the slightest physical impact and is transformed into fine dust. Perlite is essentially a swollen glass and dust that is not removed from the lungs when inhaled, so the use of protective equipment when working with it is mandatory.

In summary, we can compare pearlite and vermiculite and understand what the difference is. We can say that the materials are very similar both in their properties and in their application in construction. But they still have differences, albeit insignificant:

  1. Perlite is inferior to vermiculite in terms of mechanical strength.
  2. Perlite is characterised by strong dusting.
  3. Vermiculite exhibits elastic deformation in comparison to perlite.

Thus, the choice of a particular thermal insulation material may depend on the technical characteristics of the house under construction and be determined by the specific type of work, individual considerations and preferences of the builder. Often the economic component plays an important role. Therefore a few words about the price indicators of perlite and vermiculite.

The cost of bulk materials depends on fraction and brand, thermal insulation panels based on expanded perlite or vermiculite – on panel size, thickness and manufacturer. A comparison of the prices of perlite material and its vermiculite analogue speaks eloquently for the former. Perlite is almost three and sometimes four times less than vermiculite. To reduce the cost of using vermiculite, it can be mixed with sawdust, such a composition is often used by developers.

Use Perlite If…

  1. You have plants that need to dry out before watering again
  2. When you move your seedlings to separate pots
  3. You need to loosen clay soil in your garden

Perlite when added to clay soils, it can eliminate both surface crusting and puddles. It will also help to reduce fluctuations in soil temperatures in your garden soil. Perlite will also improve both drainage and aeration in your home gardens. Horticultural perlite can be bought in different grades according to how you’re going to use it. For general application, a fine to medium grade can be used. It’s free of weeds, disease free and sterile.

Use Vermiculite If…

  1. You need an additive for plants that need to be kept moist
  2. You want your seed trays to develop strong seedlings

Don Burke

I am Don Burke, one of the authors at My Garden Guide.  I am a horticulturist that cultivates, grows, and cares for plants, ranging from shrubs and fruits to flowers. I do it in my own garden and in my nursery. I show you how to take care of your garden and how to perform garden landscaping in an easy way, step by step.I am originally from Sydney and I wrote in local magazines. Later on, I have decided, more than two decades ago, to create my own blog. My area of specialization is related to orchid care, succulent care, and the study of the substrate and the soil. Therefore, you will see many articles dedicated to these disciplines. I also provide advice about how to improve the landscape design of your garden.

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