Pumice is fascinating stuff, borne out of the superheated earth. It is basically whipped volcanic glass that is made up of tiny air bubbles. This means that pumice is a lightweight volcanic rock that makes it perfect for use as a soil amendment.
Pumice is an excellent soil conditioner, as it is highly porous, giving it excellent water and air holding properties. The airy rock is ideal for use with cacti and succulents as well as other plants that require excellent drainage and air circulation.
Benefits of Pumice:
•Provides aeration and drainage to potting mix.
•Heavier than perlite.
•1/3 lighter than sand.
•It holds vital nutrients in the microscopic surface pores, which helps regulate fertilizer feedings.
•Loosens the density of heavy clay garden soils, letting in the air and water plants need.
•increases water retention in light and sandy soils.
•Holds moisture in the soil, reducing watering requirements, yet pumice will not compact or become soggy.
•It will not decompose or compact over time, and can be recycled and reused.
•Does not attract or host fungi, nematodes, or insects.
•Pumice can be used as a topdressing to absorb rainwater that puddles around plants.
•For potted succulents, combine equal portions of pumice to potting soil.
•For cacti and euphorbia, combine 60% pumice with 40% potting soil.