Vermiculite

 

Vermiculite is a porous, spongelike, sterile media. It’s lightweight and has a high water absorption capacity- holding up to five times its weight in water. It also has a relatively high cation exchange capacity, holding nutrients in reserve and later releasing them. Care needs to be taken in some systems when using vermiculite as a stand-alone since it is prone to over saturation when nutrients are applied frequently, often resulting in root rot.

 

Vermiculite in horticultural applications improves soil aeration, retains water and provides nutrients to feed roots, cuttings and seeds for faster, maximum growth. Blended mixes with vermiculite promotes faster root growth and allows young roots to anchor quickly. It helps to retain air, plant food and moisture, releasing them from the mix as the plant requires them.

 

Like Perlite, horticultural vermiculite is permanent, clean, odourless, non-toxic and sterile. It will not deteriorate, turn mouldy or rot. The pH of vermiculite is essentially neutral (7.0-9.5) but owing to the presence of associated carbonate compounds; the reaction is normally alkaline. It also will vary (become more alkaline) with changes in processing techniques and time, and with the presence of moisture. The pH, color and chemical composition of vermiculite also will vary from mine to mine.

Caution: Vermiculite is available at home centers and building supply companies as an additive for plaster and insulation in walls and ceilings. Do not use these products for soil conditioning. Construction grades of vermiculite do not absorb water well and are not handled properly during the manufacturing process to maintain a sterile product.  Make sure that the bag is labeled "horticultural."

Bottom Line:  Vermiculite is a viable product that has its place in horticulture, although there has been some controversy about vermiculite and asbestos.We feel that there is a better product on the market, that is both all natural and sustainable - coconut coir.