Choosing Growing Media
• Success of any plant production system depends
in part to proper root growth and development
• Root zone health tends to lead to healthier plants
with less pest problems and better yields
• Each crop has a different ideal growing medium
based on its physical characteristics
Factors to Consider in Grow Media
• Ratio between Water Holding Capacity (WHC) and
Air Filled Porosity (AFP)
– Crops need both Water and Oxygen in the root zone
– Fast growth crops tend to benefit from a balance
between WHC & AFP
– Whereas, succulents usually benefit from low WHC and
high AFP medias with easy drainage.
– Rarely, will one type of medium meet the crop’s WHC &
AFP requirements. Blends of various media are typically
needed. Unless, special irrigation techniques are used
Factors to Consider in Grow Media
• Low Bulk Density and High Porosity
– Bulk density is a measure of the mass of medium
plus voids per unit volume
– Typically, the lower the Lower the Bulk Density the
Higher the total Porosity
– High Porosity enhances gas exchanges between
roots and atmosphere
– These gas exchanges lead to more oxygen in the
root zone which has a positive effect on root
growth rates and a reduction in root diseases
Factors to Consider in Grow Media
• Bulk Density – Continued
– Air Filled Porosity is important to consider after
• Once watered how saturated is the media?
• Is there still ample oxygen levels?
• Best media should have a Total Porosity above 50% and
contain at least 25 to 30% Air Filled Porosity at capacity.
– Low Bulk Density Medium also has the benefit of
being light weight when dry (less transportation
Factors to Consider in Grow Media
• Easy to Drain
– Drainage is influenced by the Media Texture
– After irrigation the texture influences how much
water is available to the plant
– Heavy and Compacted Media hold more water
– Highly Porous Media drains Faster
• Faster Draining = faster exchange of Oxygen in root zone
thus a Healthier crop.
• Also allows for faster adjustment of fertilizer and pH
• Easy to drain media is beneficial as it prevents water
clogging and anaerobic conditions which lead to Root Rot
& Diseases
• In humid environments this is very important.
Factors to Consider in Grow Media
• Steer-ability
– Ease of maintaining the crop between Vegetative and
Reproductive growth
• Uniformity of Particle Size Distribution
– Promotes even moisture and air levels throughout
• Chemically Inert
– No or low Cation Exchange Capacity (CEC) allows complete
control over nutrients
• Reusable
– How fast does the material break-down?
• Ecological Impact of Acquisition
– Strip Mined VS Repurposed
What are Growstones?
• Growstones are a Man-Made Growing Media
– Can be used in many different applications
Hydroponic Production
Amendment to Soil or Soilless Mixes
Biofilter for Aquaculture
Mechanical Barrier for Fungus Gnat Control
Recycled Repurposed Product
• Growstones are
Made from
Recycled Glass
• Other Media is
Strip-Mined out
of the Ground
The Growstone Mine
• Our production facility is located on the
Albuquerque Municipal Landfill
• Landfills will be the mines of the future!
How we make Growstones
Recycled Glass is pulverized into a powder.
The powdered glass is mixed with a Foaming Agent and
a pH Buffer.
This mix is then spread onto a sheet conveyer and run
through our furnace. It starts its journey at ½” thick.
Our furnace is about 100ft long and reaches
temperatures of 1600 degrees.
The now Foamed Glass immerges from the furnace in a
continuous sheet. That is around 4” thick.
The Foamed Glass is cooled and crushed.
We then screen the crushed product for each of our
Growstone Porosity Comparison
Growstones have 31% Water Holding Capacity
(WHC) & 51% Air Filled Porosity (AFP)
Trials at University of AZ & WUR of
• Crops – Tomato & Cucumber
• Duration – 2 Years
• Conclusions
– Reduction in Blossom End Rot
– Faster Production of Fruit
– Yielded 4% more Fruit
– Reduction in Pythium 15 to 1
* In comparison to Rockwool Media
Soluble Silica
• Since Growstones are made from Glass they release soluble
Silica (monosilicic acid H4SiO4)
• The Si content varies between 0.25 and 1.20 millimoles per
liter (mmol/L)
• Studies at UC Davis have shown that Si increases plants
resistance to Fungal Diseases, Plant Parasites such as
Pythium and Chewing Insects such as Leaf Miners.
• Silica should be a part of an IPM program since it thickens
the leaf cuticle making it harder for pests to break the leaf
surface, reducing the need for certain pesticides.
• Fruits grown in Growstones have shown a thicker skin. This
could be beneficial during transport and a longer shelf-life.
Growstone Products
GS-1 Hydroponic
GS-2 Soil Aerator
GS-3 Coco Mix
Gnat Nix!
• Growstone GS-1 Hydroponic
– Standalone grow media
• Alternative to
Expanded Clay Pebbles
Pumice, Cinder
– Aquaponics (Fish/Plants)
• Grow media
• Biofilter
Blending with Soils
• Growstone Mix This Soil Aerator
• UofA study – increased Aeration
87% higher Air Filled Porosity
(AFP) than Perlite
• Long lasting in soil
• Holds better in mix. Doesn’t
float up
• Releases Silica
Coco Blend
• Growstone GS-3 Coco
– Premixed Soilless Grow
– 60% Growstone
– 30% Sri Lankan
Buffered Triple Washed
Coco Fiber
– 10% Redwood Fiber
Gnat Nix!
Unlike other top dresses that are limited to one phase of control,
Gnat Nix! controls gnats at different points of their lifecycle. It
prevents adult emergence from hatching larvae and deters
females from laying eggs in the growing media. As a result, the
lifecycle of fungus gnats is interrupted, and its population
significantly reduced.
No pesticide – safe for all crops
Kansas State University Trials – Effective Wet or Dry
Can be used day of harvest
IPM programs - Reduces need for pesticide soil drenches
Fungus Gnat Larva eat roots
Root damage can lead to root rot, diseases, molds, etc
• Gnat Nix! is a Top Dress Mechanical Barrier
• Should be applied to surface of grow media
• For full control rate a ½” to ¾” thick layer is
• Maintain layer for control – reapply as needed
IPM and Growstones
• A media, with proper WHC & AFP, is one part of
many that are key to overall plant health, which
in turn, could reduce the amount of pesticides
that would normally have to be used to combat
insects, plant parasites, and fungal diseases that
affect plants under stress in poor grow media.
• Growstones provide a balanced WHC & AFP plus
soluble Silica.
• Clean – No stray seeds. No harmful pests hiding.
A Revolutionary Product

Nathan Ferverda - Crop Production Services