Pumice Grow Media for Cacti and Other Succulents


cactus potted in pumice

Cacti and other succulents love well-drained soils—pumice allows enthusiasts to create the ideal soil blend to square optimum drainage rate with watering frequency.

succulents thriving in pumice soil

Drainage rates in pumice soil is easily controlled by grade choice: larger grades (stones) drain faster and retain less moisture than smaller grades. As needed, grades are grower-blended to create the ideal.

photo of Rutsu Eights pumice grow media

Rūtsu Eights™—a blend of 3/8 to 1/8-inch cleaned and dried pumice stones.

photo of Rutsu Sixteenths pumice grow media

Rūtsu Sixteenths™—3/16 to 1/16-inch cleaned and dried pumice stones.

photo of Rutsu Fines pumice grow media

Rūtsu Fines™—1/8-inch stones to powdery, water-retentive pumice fines.

rutsu pumice soil logo

SUCCULENTS, INCLUDING CACTI, love a soil that drains well, but holds onto moisture and nutrients long enough to meet the needs of the plant. That means a carefully balanced combination of soil type (grow media) and watering frequency. This dynamic, greatly influenced by climate, is the key to thriving succulents. Pumice, with its natural frothy-stone, nook-and-cranny-riven character, is widely used by succulent enthusiasts because it allows them to easily create and maintain that ideal balance.

Ideal Physical Form Factor

Pumice is a naturally-occuring (volcanic origin) foamed glass stone. On a micro level, pumice stones are sponge-like in form factor (riven with holes and hollows of various sizes) yet, being amorphous silica glass, doesn't absorb moisture and swell, but rather retains moisture by virtue of its phyical structure— 1) held within the tiny-to-microscopic pores in the foamy-stone, 2) caught on the rough, irregular surface, and 3) caught and held in the spaces between the tiny stones themselves. This type of moisture retention is ideal for controlling drainage rates. One simply adjusts the stone size blend to dial up the desired drainage rate. This same structure provides the vital aeration spaces needed by roots to expell and absorb gasses.

Control the Drainage Rate with Particle Size

By adjusting the particle size profile, pumice soil can meet the moisture needs of a wide variety of plant-types in a wide variety of climates. A pumice-soil profile can also be blended to square with how often one likes to water. Pumice soils made up of larger particle sizes drain more quickly that those consisting of smaller particles. Small stones pack more tightly together and, consequently, hold more moisture for longer.

Other Considerations

Pumice soil also finds a sweet spot in terms of weight. It is a lightweight stone, yet substantial enough not to blow away. It also provides enough weight to anchor a light pot, yet is easy on shelves and racks. The nooks and crannies on the surface also provide ideal habitat for beneficial soil microbes. By adding a quality liquid fertilizer to the water itself (common among bonsai enthusiasts), one can meet the plant's nutritional needs and avoid the use of potting soils, composts and problematic organic media altogether—pumice does not decompose or rot. Pumice is also a great media for rooting cuttings and offsets.

Pumice can also be used to amend succulent and cactus garden soils. Drainage rates can be greatly improved, and, where puddling tends to create problems, and top-dressing of pumice stone can insure the crown of the plant does not come in contact with soggy dirt.


Our Rūtsu™ branded pumice grow media (pronounced root-sue) is available in three grade sizes to provide succulent, cactus and geophyte enthusiasts with the flexiblity to blend the ideal inorganic soil for each plant. The Rūtsu Eights™ and Rūtsu Sixteenths™ grades are dried, screened and graded to contain no fines. The Rūtsu Fines™ media provides the grower with a way to blend the precise amount of pumice fines into the other grades if and as needed to meet the water needs of a particular plant.

About Pumice

Pumice is abundant and found in many parts of the world, but not all pumice is created equal. Rūtsu™ pumice media comes from a pumice deposit located in southeast Idaho on the shoreline of an ancient lake known as Lake Bonneville...a vast, freshwater lake that once covered much of North America’s Great Basin region (most of Utah and parts of Idaho and Nevada). The Great Salt Lake is all that remains. The volcano that produced the pumice (about a mile to the north of the mine) put a lot of pumice-ash into Lake Bonneville, where it was washed and stratified by centuries of relentless wave action, cleaning the pumice of the undesirable heavy minerals that are often found in other pumice deposits.

Pumice is not scoria. Scoria is common lava rock, typically red, red/brown, sometimes black, and is often used as a decorative landscaping ground cover. Scoria forms from basaltic magmas, while pumice is of rhyolitic magma origin. The difference is important. Pumice has many more vesicles—trapped bubbles—than scoria and the walls between them are very thin. Pumice is essentially a foamed glass stone, amorphous (non-crystalline) in structure. The pumice from our deposit is neutral in pH, and more tightly structured (dense) than is typical—it (for the most part) does not float.

DRIED AND PATHOGEN FREE: During processing, our Rūtsu Eights and Sixteenths grades are heated and dried, eliminating stow-away pathogens.

DRAINAGE: Drainage rates vary by grade: larger grades (stones) drain faster and retain less moisture than smaller grades.

TEXTURE: The sharp, irregular surface edges of the pumice stone help to promote fine root development and lend to a more healthy plant.

SIFTED AND GRADED: The Rūtsu Eights and Sixteenths grades have been dried and sifted to remove the fines. If water-retentive fines are needed in a particular soil profile, blend in a bit of our OneEight+Fines grade.

AERATION: Rūtsu stones are not uniform in shape, and thus provide ample air spaces between particles and amid the natural nooks and crannies found on the surface. The rough-hewn, finely-riven surface of each stone also provides ideal habitat for benefical bacterial and mycorrhizae as well as grippy purchase for decorative cover mulches.

LIGHTWEIGHT YET TOUGH: The weight-savings of our frothy pumice media can be significant, especially in larger pots. Yet the Rūtsu pumice stone media is tough—resistant to crushing and breakdown, significantly extending the replacement intervals.


» Technical Data: the physical and chemical properties of our natural pumice.

» Pumice Safety Data Sheet (PDF)

RŪTSU™ EIGHTS (Cacti and Succulents Grow Media)
Naturally pure pumice stone, dried, screened (graded) for use as Cacti and Succulents soil media.
» Size/Grade: 3/8 to 1/8-inch pumice stones (Grade 3/8x8)
Technical Data Sheet (PDF) for Rūtsu Eights™
BUY RŪTSU™ EIGHTS (Cacti and Succulents Grow Media)
RŪTSU™ SIXTEENTHS (Cacti and Succulents Grow Media)
Naturally pure pumice stone, dried and screened (graded) for use as Cacti and Succulents soil media or as a seed and cutting propagation media.
» Size/Grade: 3/16 to 1/16-inch pumice stones (Grade 8/12B)
Technical Data Sheet (PDF) for Rūtsu Sixteenths™
BUY RŪTSU™ SIXTEENTHS (Cacti and Succulents Grow Media)
RŪTSU™ FINES (Cacti and Succulents Grow Media)
Naturally pure pumice stone, top-screened for use in Cacti and Succulents soil media blends. Provides inorganic, water-retentive fines for adjusting media drainage rates.
» Size/Grade: 1/8-inch stones to powdery fines (Grade 1/8Fines)
Technical Data Sheet (PDF) for Rūtsu Fines™
BUY RŪTSU™ FINES (Cacti and Succulents Grow Media)

CONTACT US: salesteam@hesspumice.com

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