• Recycled Glass Bottles Could Replace Perlite & Pumice

    A Santa Fe-based company is days away from opening up a very cool factory. Located at the Albuquerque city dump and recycling center, Growstone, LLC, is turning used glass bottles into a substitute for perlite, used in hydroponic growing applications and as a hygroscopic (water retaining) soil amendment. My guess is that their product will also soon be seen as an excellent alternative to pumice—at least when replacing the essential ingredient in one of may favorite passive water harvesting techniques, the pumice wick.


    There’s a chapter in Harvest the Rain about pumice wicks, so you may have to buy the book (which will be out in two weeks) to learn how to install one. For now, just imagine an extra-wide, super-thick, and ultra-long, underground sponge. You plant on either side of this sponge (or wick) and the roots of your plants suckle up to the sucker like piggies on teats.


    Due to the high cost of shipping, up until recently pumice wicks were only feasible for folks who live relatively close to pumice mines. But this may be changing thanks to Growstones’s ability to ship “anywhere” in 35 cu. ft. recycled plastic bags. I met with Pat Beare, Growstones’s factory manager the other day, and he had to admit that the main focus of the company’s marketing plan has been on getting into the perlite market, but we both agreed that there is extremely awesome potential when it comes to the possible replacement of pumice for growstone (which is a registered trademark, btw).


    Both perlite and pumice are mined from the Earth and typically cause terribly negative environmental damage. I would always justify this damage because we were putting pumice to such great use as a water harvesting technique that requires no pumping (as in active water harvesting systems) and loses no water to evaporation (in passive water harvesting applications). Now that there seems to be a product that will allow us to not degrade our forests and streams while we  simultaneously use a locally recycled material, my affection for the pumice wick, er, I mean glass-bottle wick, is growing fast like the belly of a happy young hog at dinnertime.


  1. Patrick Beare, Growstone says:

    As Nate mentioned, the focus for Growstone is to be an alternative for perlite. The reason for the perlite focus is that Growstone is an excellent growing substrate for hydroponic growing systems and a soil enhancer for container gardeners – which perlite is currently the leading growing material in these applications. Both perlite and pumice are strip mined materials where as Growstone makes use of a resource (recycled glass) that otherwise would be buried in the Earth and take 4,000 years to decompose. Growstone also has many of the same characteristics of pumice, and pumice was one of the reasons that company co-founders, Andrew Ungerleider and Gay Dillingham, started Growstone and its sister company, Earthstone. They saw the destructive strip mining of pumice from New Mexico’s Jemez Mountains and looked for an alternative to pumice and also a way to make use of the mountains of glass that were being buried in our country’s landfills. Earthstone/Growstone was the result.

    Many people think that just because they drop off glass at a recycling center, or place it out for curb side recycling that it is made into a new product. In general, the opposite is true. The reason for this is, to make a new glass product, the glass must be separated by color. Glass containers come in four different colors: clear, blue, brown and green; glass must be separated by color to ensure that new glass is not created from a mix of colors. Growstone does not have to separate the recycled glass by color to produce our products. Glass takes up a lot of room in a landfill, and takes thousands of years to decompose. It is usually cheaper for a city to crush the glass and then bury it. Currently, we as a country only recycle about 28% of all glass bottles and jars that we create. Glass makes up about 8% of America's municipal waste.
    The Growstone plant is located at the City of Albuquerque’s Cerro Colorado landfill. The trucks bring the glass in and it is dumped, crushed and made into a product all on the landfill site. In addition, the City of Albuquerque will be running a pipeline to bring in methane gas from the landfill to power our kilns. None of this would be possible if it not for the City of Albuquerque’s progressive and innovative efforts to make use of the recycled materials they collect.

    Growstone eventually will have plants open throughout the United States near large recycling centers, making use of the mountains of recycled glass nationally, and with plants strategically located, lower our shipping costs to our customers. Growstone is sold by the bag at hydroponic stores and by the “super sack to commercial growers.

  1. JDG says:

    The growstone product is great for gardens. I've got it in both flower beds and my vegetable garden. I'm lucky enough to live near the plant in new Mexico and got some of the product earlier than most, and it has worked wonders to aerate local heavy soils and make the most of water resources. Further, I don't want pumice from nasty strip mines that are destroying the local mountains in my lovely garden

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