Horticulture: Soil Amendment


new lawn growing in pumice-amended clay soil

Newly seeded lawn sprouting in clay-heavy soil amended with SoiRox™ Amender XF

cut-away showing new lawn rooted in pumice-amended clay soil

Cut-away showing the rootzone of new turf thriving in clay soil amended with SoiRox™ Amender XF

new lawn bed prepped with pumice and compost

Preparing a new lawn bed: native clay-heavy soil (right) amended with SoiRox™ Amender XF (center) and compost (left) prior to till-blending and seeding. The compost will break down and disappear; the pumice will remain, providing permanent structural improvement to the clay-heavy soil.

SoilRox Amender XF

SoiRox™ Amender XF

magnificed pumice particles showing foamed-stone character

This micrograph of pumice fines shows the nooks and crannies that capture and hold moisture and nutrients for on-demand uptake by the root system. Also evident are the grippy edges that help hold pumice functionally in suspension throughout the soil matrix.

soilrox logo

PUMICE IS WIDELY USED to improve the growability of soils—combating compaction and runoff, improving friability and aeration, and holding moisture and nutrients in the root zone. The porous, foamy nature of pumice also makes for an ideal environment for beneficial microbes to thrive.

Why SoilRox™?

SoilRox™ works within the soil on two levels. The first is as a structural conditioner, physically amending poor soils—like heavy clay—to be less dense by holding the soil particles apart, creating elemental tilth and friability. This improvement in the distribution of the micro and macro spaces in the soil enhances root zone breathability and drainage.

The second benefit comes from the foamy, sponge-like nature of the pumice stones themselves: the stones—including the tiny fines—are riven with nooks and crannies and pockets that hold moisture and nutrients in the root zone and available to the root systems over a longer period of time.

Though lightweight, SoilRox is somewhat heavier than expanded perlite and vermiculite, and so does not tend to work its way to the surface over time and float or blow away. The irregular, grippy edges of the pumice stone also work to bind it into the soil matrix.

SoilRox™ is Enduring.

Organic composts are wonderful and a great addition to any soil improvement effort, but any structural improvements from the compost breaks down over time as the compost is consumed. Without a steady schedule of compost re-application and blending/tilling, the soil tightens and returns to its poor native state. SoilRox is inorganic and will not break down. It remains indefinitely in the soil, providing vital structural support. In applications that are not replanted on a annual basis—like a lawn or any other living ground cover—that’s an extremely valuable benefit.

SoilRox is easily blended with composts to provide the ideal long-term solution to fix-it and forget-it applications like lawns, parks, runoff control constructs, and reclamation projects. The compost provides the kick-start nutrient base to poor or damaged soils, with the pumice remains long after the compost is consumed to provide the elemental tilth that in necessary for the on-going vitality of the newly-established vegatative cover.

HORTICULTURAL PUMICE PURITY DISCLAIMER—Our horticultural mine grades are typically comprised of 98% pumice and 2% other igneous minerals, which are not removed through our mining processes.


» More information on SoilRox, including usage guidelines, is found on our SoilRox.com website.

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

» Pumice Safety Data Sheet (PDF)

» InfoGraphic: Determining Soil Type (Jar Method; PDF)

» Knowledge Brief: Conditioning Soil with Pumice (PDF)

» Website: SoilRox.com

» Website: Find information about soilless grow media at PonicsStone.com

SoilRox Amender XF opens up pore spaces to greatly improve drainage and aeration (gas exchange) in the root zone, with the extensive fines providing widely-dispersed soil conditioning—capturing, holding and time-releasing moisture and nutrients back to the roots. This elemental restructuring of the soil profile is permanent—SoilRox is inorganic and will not readily break down. This is especially welcome in long-term landscaped areas like lawns and ground-cover features. SoilRox is used to amend expansive areas containing poor native soils. Properly portioned and blended, this SoilRox amender grade reduces or eliminates the need for tilling, as the pumice provides elemental tilth, friability, drainage, and compaction resistance.
Typical Homeowner Applications: Turf lawns, landscaped ground covers, (including ornamental grasses and shrubbery) large garden plots, berry plots, in-ground green house beds (especially for root crops), perennial flower and/or herb gardens.
Typical Commercial Applications: Turf for parks and athletic fields, high-value crop fields, mining and construction restoration/reclamation projects, wetland builds, biofiltration systems, ecology embankments and other runoff control and filtration constructs.
» Size/Grade: SoilRox Amender XF (1/8-inch stones with extensive fines)
Technical Data Sheet (PDF) for SoilRox Amender XF
SHIPPING NOTE: We ship most anywhere. The shopping cart system is set up to auto-calculate domestic (U.S.) shipping, but for those ordering from elsewhere, please email us at fc@hesspumice.com and we’ll see what we can do. For large orders, please contact us for a freight rate.
The pumice fines in Blender SF, though not as numerous as in the Amender XF, function to further enhance moisture and nutrient retention on a micro level at a more complete in-soil dispersion rate while the larger stones enhance the aeration profile and faciliate drainage—especially important when growing in containers.
Typical Applications: General purpose soil conditioning for potted plants, hanging flower baskets, grow boxes, greenhouse beds, flower beds, and garden plots. Used in lightweight soil and soilless blends engineered for roof gardens and container plantings where soil weight/load is an issue. Also used in container soil blends where a more thorough size-range dispersion of pumice is desired. For landscaping/greenscaping applications, is used to amend native soils with some clay and silt content.
» Size/Grade: SoilRox Blender SF (3/8 x 1/8 inch stones with some fines)
Technical Data Sheet (PDF) for SoilRox Blender SF
SoilRox Enhancer NF enhances aeration as well as water and nutrient retention properties. Used in specially-crafted soil and grow media blends where elemental tilth and friability is inherent, making the for need for pumice fines to improve the soil structure unnecessary. Though lightweight, SoilRox is somewhat heavier than perlite and vermiculite, providing more substance and anchoring weight for growing top-heavy plants in pots.
Typical Applications: Blended in specialized soil (no native soil) formulations used for container-grown plants, grow boxes, greenhouse beds, seed pots, and garden plots.
Typical Applications 2: Used in specialized soilless media blends (or used straight up) to grow succulents, bromeliads, cacti. Also used by bonsai growers.
» Size/Grade: SoilRox Enhancer NF (3/8 x 1/8-inch stones with no fines)
Technical Data Sheet (PDF) for SoiRox Enhancer NF
SHIPPING NOTE: We ship most anywhere. The shopping cart system is set up to auto-calculate domestic (U.S.) shipping, but for those ordering from elsewhere, please email us at fc@hesspumice.com and we’ll see what we can do. For large orders, please contact us for a freight rate.
SoilRox Mulcher C provides a lightweight, decorative covering mulch that suppresses weed growth while insulating the soil beneath against extreme temperature swings. Works to both hold moisture in the soil and hold the soil in place. SoilRox Mulcher won't blow away like bark-type mulches can. Retains its grey-white color indefinitely. Can be easily removed and reused.
» Size/Grade: SoilRox Mulcher C (5/16-inch stones)
Technical Data Sheet (PDF) for SoiRox Mulcher C
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Contact the Pumice Store:

Product and Large Quantities Information: salesteam@hesspumice.com

Fulfillment and Shipping: fc@hesspumice.com