Vermiculite For Plants: Improvement Of Nutrient Absorption


Vermiculite For Plants: What is vermiculite?

Vermiculite for plants is known to many gardeners as a sowing substrate (5). But the silicate mineral can do much more. It can improve the soil properties and increase the rooting of plants in the soil. Since vermiculite for plants is a clay mineral, it can have a significant influence on soil fertility. However, many studies (4) reflected the presence of asbestos in vermiculite (3) utilized for insulation (1) and gardening (2).

Vermiculite is a natural mineral that is mined in open pits all over the world, for example in Brazil, South Africa, China, and Russia.

It is a natural, environmentally-friendly (clay) mineral, which is expanded in several processing steps under high heat, resulting in a light granulate of various grain sizes.

It is particularly suitable for the pre-growing of your vegetable plants:

  1. It is a very pure and sterile material due to the strong heating.
  2. Seedlings do not mold in it, since vermiculite is germ-free.
  3. The pre-growth of vegetable plants is a clean thing in vermiculite.
  4. Vermiculite stores moisture extremely well.
  5. You prefer to grow your plants in closed containers.
  6. The seedlings grow much more loosely in vermiculite than in soil and can be separated much better when it comes to pricking. This prevents root damage.

Properties of Vermiculite?

Vermiculite has always been used in professional gardening because of its beneficial (physiological) properties.

  • inorganic and sterile
  • free from pathogens, seeds, insects, and nematodes
  • low volume weight
  • excellent moisture retention
  • Good capillary properties (ideal distribution of moisture in the substrate)
Overview: Properties of vermiculite for garden and soil
Use for: Growing, improvement of soil structure, heat balance, improvement of nutrient supply
Properties: structurally stable, heat-insulating, elastic, germ-free, high absorption capacity, inorganic
pH value: neutral

Vermiculite as a substrate in the garden

Origin of vermiculite

Vermiculite is a clay mineral which is chemically classified as belonging to the group of layered silicates. All clay minerals are mainly formed by weathering of rocks and other minerals (so-called primary minerals). Before the actual formation, these weathering products are exposed to pressure and high temperatures.

Vermiculite is in itself rather platy and therefore hardly used for industrial or horticultural applications. However, in order for it to be used in its familiar form, the raw material obtained is exposed to high temperatures (up to 300 °C) once again. This is known as expanded vermiculite, in which the clay mineral is expanded to many times its original volume. The material then resembles a worm-like form, which was probably the reason for the name of this aggregate. Because of its bloating properties, vermiculite is sometimes also called expanded mica.

vermiculit.e for plants

Use of vermiculite in the garden and for pot culture

The numerous and valuable properties of vermiculite are naturally also used in horticulture. Due to its ability as a clay mineral to absorb and release cations, the aggregate plays a major role, especially in optimizing the supply of nutrients . Especially the substances ammonium, potassium, calcium, magnesium, and iron are of interest here.

Another use of vermiculite is as a growing substrate. Since the substrate is germ-free and almost pH-neutral, it is ideal for growing many plants. On the one hand, it is an excellent growing medium and at the same time serves as a heat-insulating covering medium.

vermiculit.e for plantsVermiculite is considered to be an excellent germ-free growing substrateImage source
: Onur ERSIN /

Vermiculite is often used in combination with perlites. The perlites also ensure the absorption of excess water and therefore optimize the water requirements of the substrate.

Gardeners who have clayey soils with frequent waterlogging can use vermiculite to loosen up the soil and at the same time regulate the water balance. However, it is recommended to combine vermiculite with other storage materials such as zeolite or expanded clay.

Vermiculite is generally suitable as a soil conditioner. It optimizes nutrient uptake, improves soil aeration, better regulates the heat balance, and generally has a positive influence on soil fertility. If, for example, vermiculite residues accumulate during the cultivation of plants, they should not be thrown away. This valuable material can help to better supply plants with nutrients and at the same time save fertilizer and water.

Available particle sizes of vermiculite

Vermiculite is commercially available in various grain sizes. The most common sizes are 1-3mm, 2-4mm, 3-6mm, and 3-8mm. For mixing your own substrates or growing media, the grain size 3-6mm is recommended. The grain size 1-3mm (or 2-4mm) can be used as a soil conditioner.

Furthermore, there is a vermiculite in very fine grain size (0-1mm). This plays only a minor role in horticulture and is mostly used in the breeding of reptiles as a breeding substrate.

Vermiculite in trade

The processed clay mineral vermiculite can be bought in many pet shops and sometimes in-plant shops. The prices there are usually quite high, however, so it can be worthwhile comparing on the Internet.

If you need vermiculite frequently, you should possibly purchase a large supply. For this purpose container sizes between 50 and 100 liters are available. For a 100 liter bag the retail price should be between 28 and 38 dollars. The prices can vary depending on the grain size and fines.

Advantages at a glance:

  • Optimal water and air reservoir
  • Perfect soil loosening
  • pH neutral
  • Regulation of the soil heat
  • Prevents mold growth
  • High soil fertility through ion exchange
  • Natural exchange of trace elements

Vermiculite is simply added to the soil or used as hydroponics for the germination of seedlings and propagation of cuttings. By inflating the silicate layers during exfoliation, very good water and air reservoir is formed as a capillary structure between the individual layers. These reservoirs provide a regulating water balance, store excess nutrients, and trace elements, regulate the heat balance, and loosen the soil.

Original Vermiculite is used as mulch material in nurseries. Vermiculite ensures that the soil with the seedlings is protected from drying out. Vermiculite also counteracts the formation of liverwort.

Vermiculite has proven to be excellent for dark germs.

Commercial horticulture has long been relying on the positive properties of Original Vermiculite. Simply because Original Vermiculite guarantees a long-term balanced water balance in the growing soil. The porous structure, i.e. the filigree layers of Vermiculite ensures optimal aeration of the soil and thus good oxygen supply to the plant roots.

Natural high-tech products in the agricultural sector for soil cultivation. In industrial agriculture, mineral swelling products are used for example in the fields of:

  • Breeding of young plants
  • Tobacco cultivation
  • Tomato Cultivation
  • Viticulture
  • Tulips and orchids cultivation
  • Cultivation of spawn of mushrooms
  • Loosening of clayey soils
  • Plant specific soil mixtures
  • Bedding for quick composting
  • Fertiliser carrier material

Vermiculite the universal product in garden and greenhouse

Original-Vermiculite absorbs waterlogging moisture and works more efficiently than any other product to prevent the earth from salinization or mold. Thanks to vermiculite, rotting of the root system due to too much moisture is prevented.

Vermiculite has a neutral pH value of approx. 7.0. This results in an additional stabilisation of the growing medium.

The vermiculite fill is a natural mineral, which means it does not rot and is frost and temperature resistant.

Horticulture & plant breeding with vermiculite

Original Vermiculite has a fine capillary material structure, which offers absolute advantages especially in horticulture and plant breeding:

  • Optimal water storage
  • Nutrient Storage
  • Air storage

Perfect root development

Vermiculite is a granulate in various grain structures, from a few millimetres to 1 cm in diameter. This granulation regulates the even release of nutrients in a targeted manner and ensures improved growth. Thousands of air pores cause a loosening or aeration effect for the soil. This natural loosening effect ensures a better development of the root system of the plants.

Vermiculite against cold

Original vermiculite is the perfect insulator. Therefore it prevents the soil from cooling down quickly. Especially heat sensitive vegetables and flowers thrive optimally on vermiculite.

Multiple winner Vermiculite

In addition, the use of vermiculite in agriculture is justified both on the stage of germination and production of cereals and plants when grown outdoors.

In greenhouses, good results are achieved when combined with peat and vermiculite and recorded a positive effect when it enters the composting mass.

Vermiculite is also used for storing fruit and vegetables (potatoes, carrots, apples, pears, etc.) and landscaping.

Expanded vermiculite has all the unique properties of natural mica: low thermal conductivity, fire resistance, chemical inertness, and safety. Vermiculite has a low bulk density of only 30-100 kg / m3 due to its expansion. It has a high water absorption coefficient (100 g vermiculite absorb 400-530 ml water).

It easily absorbs moisture and also easily passes it on to the plant, creating an optimally moist environment for root nutrition. It is biologically resistant: it is not subject to degradation and decay under the influence of microorganisms, it is not a favorable environment for insects and rodents. Vermiculite is a chemically inert material (neutral to alkalis and acids).

It has unique ion exchange properties. Due to the content of oxides of trace elements such as calcium, magnesium, potassium, aluminum, iron, and silicon, vermiculite is an effective stimulator of plant growth. Vermiculite is a highly porous mineral whose flakes contain air. Its structure makes it possible to obtain the necessary aeration properties from the subsoil, where the soil does not cake up, the crust does not form on its surface but remains loose.

Vermiculite in its pure form can be used to root cuttings. Due to the fact that the mineral cannot rot or decompose, various microorganisms and fungi do not live in it. This favours rooting. Vermiculite prevents the occurrence of various rotting, mould.

Asbestos In Vermiculite, Campers, And Plaster 

As we stated at the beginning of the article, there was asbestos detected in the vermiculite utilized for gardening and horticulture. In the United States, it was also detected in retro campers and plaster. Ensure that the vermiculite for plants that you purchase is asbestos-free.

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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