Pumice 7-20mm 25L

Pumice is a light siliceous vesicular volcanic rock that forms during explosive eruptions and is suitable for use in horticulture and hydroponics.
Code: 9327719006361
Availability: Limited Stock
$ 39.90

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Pumice is an ideal growing medium for plants. Growing healthy plants, is all about the quality of the soil. Pumice has a variety of characteristics making it useful throughout your garden.  Coarse‐grind pumice rock makes an excellent and attractive mulch for flower and shrubbery beds.  The soil beneath the mulch stays moist longer and is less likely to compact from watering. Weed problems are minimized with a couple of inches of pumice mulch. It does not break down, so does not need to be replaced. Also great for Composting. Pumice rock is a great bedding additive to your worm composter. It adds additional air space, prevents matting, and helps to control moisture.


It resembles a sponge because it consists of a network of gas bubbles frozen amidst fragile volcanic glass and minerals. All types of magma (basalt, andesite, dacite, and rhyolite) will form pumice. During an explosive eruption, volcanic gases dissolved in the liquid portion of magma expand rapidly to create a foam or froth; in the case of pumice, the liquid part of the froth quickly solidifies to glass around the glass bubbles. 

Its porosity provides air spaces that maintain aerobic conditions around the roots while water is contained within the pores. Surface tension around the outside of the pumice particles increases water-holding capacity of the growing medium. Our pumice is mined from a land based resource, within 50kms of Lake Taupo, the original source of the aggregate. As a result our pumice is characterized by its relative hardness and lightweight in comparison to competing aggregates. 

The washing and screening of our pumice particularly for horticultural applications means that no ‘fine’ particles are included. Unwashed pumice can cause ‘concreting’ and higher water holding capacity than required, consequently effecting root development. This hardness and porosity allows free drainage lowering the risk of root-rot diseases. 

Permanent, Weathered, Strong, Highly Porous, Inert, Long Life Growing Media, extensively used in commercial Horticulture for a range of applications.  pH 6.9  (near neutral out of the bag) Non-toxic and naturally proven by nature as perfect for fresh water fish growth, abundant in volcanic regions like NZ, proliferating with Trout and aquatic life, swimming in Pumice lined streams. Pumice is clean ready to use, out of the bag.  Abundant high quality, local regional sources. 500 m2/litre of surface area for optimised bacterial colonisation to enhance organic breakdown, just as nature intended. Pumice per unit volume is inexpensive, sufficiently so, to be continuing to gain market share in the commercial horticultural sector, bonzai, orchids, fruit trees and numerous other specialist applications.

Pumice has a Zero Carbon Footprint.  Minimal energy is required for simple screen grading, solar drying & packaging. Compare this to glass which requires nearly half a litre of petroleum equivalent energy value, for each kilogram of glass products produced, energy needed to raise the temperature of both new and recycled glass to 1,575 degrees C the melting/forming temperature.  


Pumice is another ideal growing medium for cacti and succulents. The hardness and porosity allows for drainage, lowering the risk of root diseases The soil beneath the mulch stays moist longer and is less likely to compact from watering. 

Our pumice grades supplied for horticultural uses include:  1-4mm / 1-7mm / 4-10mm / 7-20