Frequently Asked Questions

PRODUCT KNOWLEDGE
The following information gives a basic understanding of what “is” the Growstones™ product.

1.)What are Earthstone’s Growstones made from? (Raw Material)
Growstones are made from recycled glass beverage containers received from either the land-fill or another source collecting and processing waste glass. The glass containers are 1st crushed into small glass pieces and then ground into a fine powder (consistent with the size and the feel of flour.) This “glass powder” is the main component in Earthstone (about 99% pf the finished Growstones.) A natural foaming agent is then added to the “glass powder” before it is heated and expanded in the Earthstone kilns. To see photos go to Manufacturing Process.

2.) What are the physical characteristics of Growstones?
Growstones are described as: Rigid, porous glass foam media. Growstones consist of glass foam media made from recycled glass containing approximately 95-99% vitreous soda lime glass (inert glass) with 0.5-5.0% of calcium carbonate.
Particle Size:
Hydroponic Particle Size – 1/2"-1"
Soil Amendment Particle Size – 1/16"-7/16”

The Bulk Density of Growstones is .18 g/cm3.

Growstones have a 35% water holding capacity.

Growstones have a 53% air fill porisity.
For more detailed information and to view the Growstones MSDS sheet please go to MSDS.

3.) How does one use Growstones?
This question must be answered in (2) parts, because Growstones can be used in (2) very distinct and different ways. The first and most simple way to use Growstones is as a soil amendment for the cultivation of potted crops, container gardens, flowering beds and/or landscapes. Simply mix Growstones Soil Amendment in to your mix at a 10-30% ratio depending on plant material and climate. See Products Page for specific information or call one of our technical specialists for recommendations.

The second application is for use as a hydroponic growing substrate/media. These three easy steps will allow for easy use in most all hydroponic situations: (1) Rinse by submerging Growstones in a bucket of water (2) Volume of water should be approximately four times the volume of Growstones (3) Discard rinse water in the garden. For detailed directions please go to Labels or call a technical specialist for recommendations.

4.) Has anyone else tested or used Growstones?
Earthstone has invested time and money in testing Growstones. One can visit our Gallery to see images of trials done at commercial greenhouse and universities across the globe.
Research has been done at: The University of Arizona and The University of Wageningen (The Netherlands). Field Trials have been done at: NYC Science Barge, Commercial Greenhouses in Texas, Minnesota, and Florida; as well as by Hobby Hydroponic Stores, Garden Centers and Interiorscapers across the US.

5.) How can one purchase Growstones?
To purchase or get a listing of distributors and stores in which to purchase Growstones, please call 469.532.2261.