Horticultural Grade Pumice

In-Soil Performance vs. Perlite

Pumice has lower carbon footrpint!

Perlite is arguably the most recognizable and widely used non-compost soil amendment in horticulture, especially for potting and garden soils. It is valued for its contribution to desirable soil structure and water and nutrient retention. But the process of flash-heating perlite ore to expand it adds to the cost and the carbon footprint of perlite, and that cost make the use of perlite prohibitive for large-scale amendment projects.

There is no performance drop using pumice. A University of Illinois study5 evaluated pumice as a perlite substitute for amending growing soils. Specifically, chemical properties and surface characteristics were compared and proved analogous, with pumice exhibiting a greater pore size span. From the report summary: “Pumice and perlite were shown to have similar physicochemical properties which subsequently translated into similar behavior in blended soil mixtures. It proved equally, if not even more effective in some ways than perlite. A subsequent companion plant growth study (not reported herein) further confirmed the suitability of pumice as a soil amendment. Plants grew equally well in pumice and perlite media.”

[5] Evaluation of Pumice as a Perlite Substitute for Container Soil Physical Amendment. Dianne A. Noland , L. Art Spomer & David J. Williams; Department of Horticulture, University of Illinois, 1201 South Dorner Drive, Urbana, 61801–4720