Potting soil

[2] Other materials used include rice hulls, sand, vermiculite, and calcined clays.

[4] Mediums used for growing plants in pots typically are a mix of organic and inorganic ingredients.

[5] Good growing mediums have a number of properties including moisture and nutrient retention capacity, quick water infiltration, pore space for aeration (plants roots need oxygen), drainage for excess water, decompose slowly, and provide support for the plants growing in them.

[7] The removal of the layer of CO2 absorbing plants releases CO2 into the atmosphere, contributing to climate change.

Vermiculite contains some calcium and magnesium, but more importantly it helps retain water and nutrients in the porous structure.

As an approximation for indoor home planting, the mix is generally treated as greenhouse growth medium.

[20] Commercially available potting soil is sterilized, in order to avoid the spread of weeds and plant-borne diseases.

For example, the fungus gnat is often found around houseplants because it lays eggs in moist potting soil.

[22] Infections of Legionnaires' disease due to potting mix have been reported in Australia,[23] New Zealand,[24] the Netherlands,[25] the United States,[26] and Japan.