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Perlite and Vermiculite - what are they?

We know - it keeps you awake at night - but what is the difference between Perlite and Vermiculite?


Perlite is a naturally occurring, non-toxic volcanic rock.  It is heated to very high temperatures to produce a lightweight micro-porous material. Perlite is used in horticulture as a soil amendment. Because of its high permeability / low water retention it helps to prevent soil compaction. Available in 10ltr and 100ltr bags.

A handful of Perlite
  • Perlite is used wholly or partly in place or sand or grit in potting compost where it improves aeration, draining and insulation, and also facilitates re-wetting. Perlite speeds up rooting and reduces the risk of damping off.  It provides an optimum balance of air and water -  makes water logging almost impossible.
  • Improves the texture of heavy silt or clay soils by increasing aeration and drainage.
  • Perlite is free from disease, weeds and insects.
  • Perlite improves aeration and drainage in compacted and poorly drained areas on old lawns and also helps the establishment of new grass. Perlite will greatly assist the air-moisture balance and ensure better root development and grass (lawn) growth. Use a hollow tine spike all over the affected area, then spread a thin layer (2-5mm) of damp perlite pre-mixed with a suitable fertilizer. Rake or brush evenly, and water thoroughly.
  • Perlite is better for cuttings due to to its high macroporosity. Cuttings tend to benefit from having access to lots of oxygen as well as water.


Vermiculite is an odorless mineral that is obtained through mining.  When heated it expands considerably enabling it to absorb a large amount of water.  It is often used to improve soil aeration, drainage and increase mineral availability.  Available in 10ltr and 100ltr bags.

    •  Vermiculite soaks up water like a sponge. It holds that water until the soil starts to dry out then releases it. This is good for moisture loving plants but not so good for plants that like dryer soil.
    • Unlike compost, which eventually breaks down into the soil, vermiculite doesn't break down. Compost does add vital nutrients, but if you need to permanently improve drainage, vermiculite is a great solution.
    • Vermiculite is pH neutral, around 7.0 or so, but because of some compounds found within it, it can slightly raise pH, a plus for acidic soils.
    •  Vermiculite naturally reacts with soil compounds and makes available other nutrients such as calcium, potassium and magnesium.
    • Vermiculite can be used in the storing of bulbs and root crops to help prevent rot.  Remove excess soil from bulbs and tubers and dry outside.  Store in containers in a cool dark place, covering with Vermiculite.   The absorptive power of vermiculite acts as a regulator that prevents mildew and moisture fluctuation during the storage period. It will not absorb moisture from the inside of stored tubers, but it does take up free water from the outside, preventing storage rot.
    • Our Vermiculite is medical grade which means it is free of any hazardous substances and completely safe to use.

Therefore, in summary -

What should I use to - Vermiculite Perlite
Add to a potting mix  to increasing water-holding  for improving drainage
Improve water retention Yes
Improve aeration Yes
Encourage seed germination  Yes
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