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Using Perlite In Potting Soil

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A Good Balance Of Perlite In Potting Mix

Perlite in Potting Soil

Perlite is the snowy white granular particles that look like small pieces of Styrofoam you will see in many potting mediums.

Perlite is formed when volcanic mineral rock is heated quickly causing it to expand and explode. The result is a very lightweight, porous material that is hard and does not break apart easily; it is sterile, has a neutral pH and can hold 3-4 times its weight in water yet will not rot or become soggy.

Photo of perlite

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Medium grade perlite is best to use in potting mixes for seeds and seedlings.

The principal value of perlite in any potting medium is providing aeration and improving water drainage.

Photo of perlite in potting mix for starting seeds

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The surface area of perlite particles are covered with tiny cavities that hold moisture while the particles themselves create tunnels in the mixture that allow air and water to flow freely to the roots.

Photo of vermiculite on top of potting mix

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Perlite can also be used on top of potting mix to cover newly sowing seeds in trays or pots.

Germinating seeds have no trouble pushing their way to the surface through this layer.

Photo of perlite-top-of-pottingmix-roots

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 The most important aspect of growing seedlings is healthy roots. Perlite in potting soil provides that all important environment.  

Photo of seedling grown in perlite only

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Perlite is one of the best media for growing plants, it is possible to grow most plants in perlite alone and is just as successful as traditional peat mixes.

Photo of growing-bush-beans-double-row

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However there are no nutrients in perlite. So fertilizer must be added as soon as the first true leaves appear. 

other uses for Perlite

Perlite has many application, including being one of the major components in horticultural growing mediums of many kinds.

In the garden you can use perlite to open up air ways in heavy soils by sprinkling the granules over the surface of your garden before you start planting. Wet it down to moisten it and work the perlite into the top 4 - 6 inches (10-15 cm) of soil.

Some hydroponic systems use perlite as the sole growing medium with only water and nutrients added.

Roots grow unencumbered in perlite making it excellent for rooting cuttings, place cuttings in the perlite to a depth just past the lowest leaf nodules. Seal in a plastic bag and place in indirect light for two to three weeks. Plant cuttings in potting soil when roots reach 1/2 to 1 inch in length.

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