Category Archives: Sustainability

Hortidaily Says Growstones are a Dream Substrate

By Boy de Nijs

Growstones in Bato buckets in a commercial greenhouse trial in 2009 with tomatoes.  Growstones in Bato buckets in a commercial greenhouse trial in 2009 with tomatoes.


Crushed glass has growing media. It may sound a little crazy, yet controlled research trials done by Wageningen University and The University of Arizona/Controlled Environment Agriculure (CEAC) show that plants thrive very well on foamed glass aggregates manufactured for horticulture applications. This is how Growstone, Inc. was born in 2005. The substrate is already available for the hobby grower, but currently Growstone is looking to widen it's reach and transit into the commercial greenhouse market.

At the time the first trials were done by the University of Arizona, Paula Costa was a graduate student at Agriculture & Biosystems Engineering Department. "I was finishing my research project at the CEAC and very quickly got directly involved in setting the first informal greenhouse trials with Growstones crushed foamed glass in the Fall of 2005," says Paula who is now Growstone's R&D Director.

Urban Farming Is Growing a Green Future



Photograph by Anthony Behar, Sipa Press/AP
by Green Gotham

With seven billion mouths to feed, human agriculture exerts a tremendous toll on the planet, from water draws to pollution, and from energy use to habitat loss. But there is also a growing set of solutions, from organic agriculture to integrated pest management.

More people around the world are taking a look at urban farming, which offers to make our food as "local" as possible. By growing what we need near where we live, we decrease the "food miles" associated with long-distance transportation. We also get the freshest produce money can buy, and we are encouraged to eat in season.

America’s Next Agricultural Revolution Will Happen Indoors

America’s Next Agricultural Revolution Will Happen IndoorsWith climate change wrecking havoc on the world’s crops, it’s time to consider other options. Warehouse farms might be the answer to the global food crisis.

The United Nations Intergovernmental Panel on Climate Change recently released their first report in seven years, and like many sequels, it wasn’t good. Beyond melting ice caps and unprecedented heat waves, the news that most shook readers was that "all aspects of food security are potentially affected by climate change."

Early proof of this impending disaster is playing out in California where farming-related losses in 2013 are estimated to be $5 billion and 2014 is not on track to be any better. Chipotle noted in a recent investor letter that they might cut back on their signature guacamole because of avocado scarcity. In a wry twist, this news caused much more concern for many Americans than the United Nations Nobel Prize winning team’s research tome of impending doom.

Why You Want to Kiss Clay Pebbles Goodbye

Clay pebbles available today

Growers have had a love hate relationship with clay pebbles for years. Now there’s finally a choice. Besides the clear advantage of providing a higher level of aeration than clay pebbles, Growstones have significantly less fines, and release silica over time in a form plant roots can uptake.

Here are some of the advantages of Growstones aggregates over clay pebbles based on actual physical characteristics of both substrates.

1. Higher air-filled porosity

At field capacity (i.e. after irrigation water has drained away), clay pebbles air-filled porosity is about 42%, while Growstones hydroponic media is 48% by volume. This corresponds to at least 12% higher aeration in Growstones than clay pebbles. The importance of high porosity in hydroponic growing cannot be undermined. Ideal substrates have small and large pore spaces. When the substrate is irrigated, water is held in the small pores but quickly drains through the large pores, allowing fresh air to flow through the soil, bringing oxygen to the roots and removing carbon dioxide from the root zone.

The Importance of Buffered Coco and Why We Use It in GS-3 Coco Mix

As I am sure you know, coco peat or coco coir are byproducts of industries that use coconuts. Coconut tree plantations are found in the tropical and subtropical areas of West Africa, Asia, South America and Central America. Garden grade coco coir is created by a series of steps like aging, washing, rinsing, drying, buffering, grinding, and grading. Without proper processing, coco coir will have an excessive salt content, degenerate and compact resulting in problems with Pythium root rot, and lead to nutritional imbalances especially related to calcium and magnesium deficiencies.    

Without going into too much chemistry, we'll explain cation exchange and coco coir. Since coco coir has a negative charge, it can hold certain nutrients and keep them from the plant (nutrient lockup = BAD). Suppose you are growing a fast growth annual flowering plant. You want every bit of calcium to get utilized by your plant. Nutrient lock up will affect plant health and reduce overall yields. 

So, how do we make sure our coco coir doesn't contain a lot of elements that will lock up expensive fertilizers, burn plants with excessive unwanted salts, and reduce plant health and yields?

The Science Behind Gnat Nix for Fungus Gnat Control

gnatnix-illustrationDid you know that potted soil from garden centers often is contaminated with eggs and/or larvae of fungus gnats? That means before you even start, you could have a fungus gnat problem and not even know it. Whatever the source of your fungus gnats issue, larvae are the source of plant damage. They feed on algae, fungi, decomposing organic matter, and plant roots in the growing medium. They prefer feeder roots and root hairs, both of which are important for plant health and vigor. If these roots are damaged plants may lose vigor, wilt, have poor growth, leaves may turn yellow and drop.

What’s more, even though adult fungus gnats don’t bite or feed, as long as they are able to complete their life cycle, there will always be potential for plant damage from larvae. Up until now, there was no way to significantly disrupt a gnat’s life cycle without the use of chemicals.

Not any more.

Time Is Money! GS-3 Saves You Both


Time to a grower is crucial. Why waste it measuring, blending, and preparing your blend? Did you add enough? Did everything get evenly mixed? Without the proper blending equipment, it’s a guessing game. Inevitably, you will have that ½ bag of something left over taking up space. All of this can be a waste of your time, which ultimately is a waste of your money. Not anymore.

We’ve done all the work for you!

Growstones hit the roof with Rooftop farming in Brooklyn

Edenworks family

This is a guest blog by Jason Green of Edenworks. Growstone is collaborating with this Brooklyn-based startup helping to build the future of urban farming. 

Presently, cities are largely hubs of consumption, but there’s a growing tide that is instead moving cities toward becoming closed and renewable ecosystems. Much of the driving force behind this change is increasingly conscientious consumers demanding locally and sustainably grown food. But a gap exists between the availability of this local produce, especially in cities, and the ever-increasing demand.

Some technologies, like hydroponics and aquaponics, offer a glimmer of hope for solving this problem. However, large scale systems are expensive to build, require significant expertise to operate, and are further constrained by the uniquely cramped and vertical environment of cities.