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Vermiculite is a brownish coloured, spongey particulate that can hold 3-4 times its own weight in water. While still retaining great drainage and air content, it helps to improve the water holding capacity of a substrate, reduce compaction and improve the overall conditions in a variety of situations. Vermiculite is something that is often compared to perlite, but its properties are actually quite different to its pearly white cousin. Although it is made in a similar way, but starting with a mined ore material, the resulting physical properties are quite different and can be highly advantageous for a variety of hydroponic grow rooms.

  • Improve soil structure
  • Relatively high water holding level
  • Easy to add into potting mix as an amendment
  • Natural source of silicon

What Is Vermiculite

Like perlite, vermiculite is an expanded natural material, only this time it is a hydrous phyllosilicate mineral Initially starting its life as a rock like material mined from places around the world like Russia, China and South Africa. The raw material is heated up to an extremely high temperature and they quickly expands, as the moisture inside evaporates, forcing it into a highly porous material filled with micro-pores of space.

During the heating process, the temperatures are raised up to over 1000 degrees C. This is called exfoliation. The evaporating moisture inside the rock forces an expansion and creates many hydroscopic micropores as it does so. This changes the composition of vermiculite to one that has a high water holding capacity, high Cation Exchange Capacity (CEC) and medium drainage/aeration levels.

How Vermiculite Works

How vermiculite works and particularly how it differs to perlite is down to a few of its physical characteristics. The Cation Exchange Capacity, water holding capacity and its air-filled porosity.

Unlike perlite with a low Cation Exchange Rate (CEC). This means how well the substrate holds on to nutritional elements like Nitrogen, Potassium etc. Vermiculite has a relatively high CEC, being able to provide quite some storage for extra nutrients within your substrate. It also has a much higher water holding capacity than perlite, so provides a much greater buffer for water. Lastly its air-filled porosity (how much air space it has) is relatively lower, so is not quite as free draining as perlite.

How To Use Vermiculite

Vermiculite comes ready to use, simply open the bag and pour it out and use it! No pre-treatment is needed of any kind, so no extra work involved other than a quick mix into the substrate. As a standalone product it retains quite a large amount of water, and so is usually best to use as part of a peat or coco mix. Most commonly used in combination with perlite at ratios of anything up to 50:50. Depending on your overall circumstance the ratio can be tailored to your exact needs, depending on plant type and of course environmental conditions in your grow room.

TIP - A mix of 50:50 vermiculite to perlite is a common method used as a substrate in propagation times when rooting cuttings. The mix makes an effective rooting media through the combination of the two distinct properties of the substrates.

Sold in 100 litre bags.

Questions & Answers

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  • What's the size grade ?

    Hi there,

    Our vermiculite grade is V3 Medium, which is a nominal size range 2.0-5.0mm.

    Kind Regards,

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