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Vermiculite Definition, Key Properties and Applications

Ecofarm Africa Connections Limited is the leading exfoliator and supplier in Kenya of high-quality exfoliated vermiculite.

Vermiculite  is a mineral that occurs naturally and expands into long strands when exposed to heat through a process known as exfoliation. The exfoliated vermiculite is light in weight and has poor thermal conductivity.

Pros & Cons of Vermiculite

In Kenya, exfoliated vermiculite is mainly used in agriculture, horticulture, animal feeds, construction, thermal insulation such as pizza ovens and furnaces, sound insulation, fireproofing among many other applications.

Our vermiculite comes in various grades, from large, coarse, medium, fine, and superfine.

Our company sustains the momentum, always conquering new milestones and strong in its long-standing belief that the best is still on the way.

Key Properties of Vermiculite

  • Lightweight
  • Chemically and biologically inert
  • Low thermal and electrical conductivity, good thermal insulation
  • Odourless and high liquid absorption capacity
  • Non-combustible, low density
  • Fusion temperature of  1260°C
  • Good Aeration

Roots must have an adequate level of oxygen from the soil and aeration is the process that facilitates oxygen exchange.

  • High cation exchange capacity (CEC)

CEC indicates the value of a soil to retain cation nutrients. The cation process captures available nutrients, ammonia (nitrogen ions), magnesium, potassium, and calcium for slow release

  • Thermal ‘insulating’ properties
  • Vermiculite has excellent insulation properties
  • Neutral Carrier

Vermiculite is a registered animal feed carrier used in pre-mixes in the animal feed industry.

  • Fireproofing

Vermiculite aggregates have been used in fire-proofing products for decades.

  • High water retention capacity optimizing water efficiency

It enhances germination, root, and shoot development. Vermiculite continues to provide the benefits of moisture retention throughout the growth cycle.

Vermiculite mix for soil improvement

Uses (Applications) of Vermiculite

In general coarser grades of vermiculite are used for loose-fill insulation and horticulture, whilst finer grades are used in building boards/plasters and in carrier applications for animal feeds and fertilizers.

Below are some of the main sectors where vermiculite is used:


Vermiculite for seed germination

  • Seed Germination
  • Blocking Mixes
  • Hydroponics
  • Micro-Propagation
  • Potting Mixes
  • Sowing Composts
  • Absorbent Packing for Hazardous Goods
  • Brake Pads & Brake Shoes
  • Castables
  • Fireproof Safes
  • Fixation of Hazardous Material
  • Furnaces –e.g for Industry and Tobacco Barns
  • Insulation Blocks & Shapes
  • Insulation – High & Low Temperature
  • Molten Metal Insulation
  • Nuclear Waste Disposal

What is Vermiculite Gardening? | Kellogg Garden Organics™

  • Soil Conditioner
  • Animal Feed
  • Anti-Caking Material
  • Bulking Agent
  • Fertilizer Carrier
  • Pesticide Carrier
  • Seed Encapsulation
  • Acoustic Finishes
  • Passive Fire Protection
  • Floor & Roof Screeds
  • Insulating and Light-Weight Concrete
  • Gypsum Plasterboard
  • Loose fill Loft Insulation
  • Sound Deadening Compounds

In-depth Discussion of the Various Sectors Where Vermiculite is Applied

Agricultural/Horticultural Applications of Vermiculite


  • Improves aeration
  • Increases moisture retention
  • Excellent cation exchange properties
  • Minimizes fertilizer leaching
  • Has a near-neutral pH
  • Inorganic and Sterile

Advantages of Vermiculite in plants

  • Promotes early germination
  • Plants survive longer in seasons of dry spells due to increase moisture retention
  • For crops under irrigation, it means less water required per hectare, thereby saving on energy costs, machine wear and tear, and labor costs
  • Improves oxygen supply to roots
  • Excellent cation exchange properties result in high nutrient retention
  • Improves yields
  • Excellent for pest and disease control

How to use Vermiculite in Horticultural and Hydroponic Industry

Vermiculite - Pure Hydroponics

Exfoliated vermiculite is an excellent growing medium and can be mixed with peat and/or pine bark. When used on its own it is necessary to add nutrients. Vermiculite has different grades and is packed in different quantities. It is important not to squash the vermiculite as the material is friable/easily crumbled. The air trapped between the laminae is important to the life of the plant. The word Hydroponics is derived from Greek meaning water and work. In hydroponic propagation, plants are grown in sterile growing media such as vermiculite.

CUTTINGS- Simply place cuttings (preferably treated with a growth hormone) into wet Vermiculite (exfoliated vermiculite). A mixture of Vermiculite/peat may also be used in the proportion 50.50 by volume. Place cuttings in semi-shade and mist over light each morning till the cuttings take.

SOIL CONDITIONER- Mix Vermiculite in roughly equal proportions with clay soil (by volume) in order to absorb the excess water. Similarly, equal parts of Vermiculite mixed with sandy soil will help to aerate the soil, stop compaction and it will improve both its water-holding capacities and its surface tension.


Grain size (mm)  Peat (%)      Vermiculite (%)               Application

1-3                               0                      100               Quick germination of fine seed

2-5                              0                      100              Quick germination of large seed

1-3                              50                     50                Slow germination of fine seed

2-5                             25                      75                Slow germination of large seed

2-5                             50                      50          Soft wood cuttings: on open bench

2-5                             25                      75              Soft wood cuttings: under plastic

2-5                             75                      25              Potting mix for house plants

0-5                            60                      40              Potting mix for vegetable plants

2-5                             75                      25               Potting mix for bedding plants

LAWN CONDITIONING- Fork/Spike the area well and then sprinkle vermiculite over the surface. Brush or water the vermiculite into the open areas. Alternatively, mix exfoliated vermiculite with lawn food before watering. Ideal for golf courses.

SEED SOWING- Sow seeds into pure Vermiculite or mix with peat/pine bark in seedling trays. Press seeds down firmly and cover with a layer of Vermiculite and mist (spray) with water daily. Seeds will germinate within a few days. It will however be necessary to add nutrients after a few days as Vermiculite is sterile.

Transfer of the seedlings into the growing beds will be easily accomplished as the roots will be protected with Vermiculite which will also act as an insulating and moisture-retaining medium.


  • Vermiculite is sterile so avoid contamination with dirty tools, infected soil, etc.
  • Plastic and Polystyrene seedling trays should be cleaned by steam or with a mixture of bleach and water to kill bacteria from the previous growing season.
  • Vermiculite is sterile and will therefore need to have nutrients added to the growing mixture.
  • It is difficult to cover the requirements for all vegetables as well as flowers/seedlings but a mixture of 50:50 Vermiculite/peat is a good foundation once the seedling has germinated and grown to about 4 leaves in the seedling “plugs” (or the pure Vermiculite starting medium). The pH may be corrected to suit individual requirements.

Industrial Applications of Vermiculite

  • Vermiculite as an insulator in building and construction

5 Things You Need to Know About Vermiculite | Family Handyman

  • The uses of vermiculite are varied and utilize many of the properties such as those in the building products and horticultural sections. For example, exfoliated vermiculite is replacing products such as asbestos which has proved to present environmental hazards.
  • Brake Linings- Finer grades of exfoliated vermiculite are being used to replace asbestos in brake linings in the automotive market. In some cases, crude vermiculite is used. This is because vermiculite is heat resistant, easy to add with other raw materials thereby achieving a homogenous mix, shape, and surface characteristics.
  • Insulation mixes- Exfoliated vermiculite is usually combined with calcium aluminate cements and other aggregates such as clay and slate to produce insulation concretes. Apart from insulation importance, mixes containing vermiculite are also used in areas where strength and corrosion/abrasion resistance are of importance.
  • Furnace Insulation- Vermiculite-based blocks and boards, which are typically silicate bound are often used as back up or hot face applications in furnaces.

Vermikulite Dome Garden Pizza Oven : 6 Steps (with Pictures) - Instructables

  • Packaging- Due to its low density, ease of pouring around complex shapes, ability to withstand shock/impact caused by improper handling, clean and inert nature, fire resistance, and absorbent capacity which minimizes leakage in the event of breakage, larger grades of exfoliated vermiculite are used in the packaging market. Also ideal for hazardous chemicals.

Construction Applications of Vermiculite

  • Building products– Vermiculite is used in building products because of its low density, good insulation properties, and fire resistance qualities.
  • Building boards–  Many boards are manufactured by adding potassium and/or sodium silicate to the aggregate until the resultant mixture is ‘earth damp’, this is then hydraulically pressed into shape in a mould, and then heat-cured at the appropriate temperature for up to 24 hours depending on the thickness of the board. Boards manufactured this way can withstand high service temperatures. This process can also be used to manufacture acoustic panels.
  • General building plasters– Vermiculite is used in general building plasters, both hand and spray applied to improve coverage, ease of handling, adhesion to a wide variety of substrates, fire resistance, and resistance to cracking or shrinkage. Vermiculite may be used on its own in plaster formulations or combined with other aggregates.
  • Specialist plasters– including fire protection and acoustic products where vermiculite is combined with a binder such a gypsum or Portland cement. Exfoliated vermiculite is used in structural fire protection mixes to improve application and to impart a high degree of fire resistance. It is efficient at retaining moisture and in the event of fire, this turns to steam which has a cooling effect on the steel substrate and thus delays its temperature rise. It is also used as a constituent of some acoustic plasters which are generally applied to ceilings or the higher areas of walls to control the echo/reverberation time in contained interior areas such as those found in offices, swimming pools, conference centers, courts, concert halls, etc
  • Roof and floor screeds– Exfoliated vermiculite especially the finer grades can be added to Portland cement and other aggregates, placing acids and water to produce roof and floor screeds which have the benefit of being lightweight and insulating

Vermiculite Grades & Industry:

  1. Large Grade – Insulation/Concrete Refractories/ Packaging
  2. Medium Grade – Insulation/ Horticulture/ Refractories
  3. Fine Grade – Horticulture/ Friction
  4. Superfine – Friction/ Animal Feeds/ Screeds
  5. Micron – Friction/ Animal Feeds