Rock Dust – The secret to a vibrant garden!

Jan 2 2020 | posted in: Rock Crushers | 0


by Titus Nelson

Cat 6 Tools, LLC

This article is on making your own rock dust for garden use. This can be done with the use of a small, inexpensive rock crusher that makes a fine dust, and much cheaper than rock dust that ranges in prices from $1.00 to $10.00 a pound.  The beauty of making your own rock dust is that you can select your own rock type, dump it in and out comes your own unique blend of rock dust.  If you were to purchase 100 pounds of rock dust at $10 a pound you have nearly paid for you Rock Crusher.

The RC-1 Portable Rock Crusher

Shown below is the RC-1 Portable Rock Crusher that works with a 5 gallon bucket.  This machine is made specifically for prospectors to grind up gravel for processing.   However, it is also perfect for the homeowner. It can be loaded in the car and taken to the field, loaded with river rock gravel or volcanic basalt.  Just grind up the rocks and keep the dust in buckets for further use, processing,  or to make up your own custom soil blend.

Click here for more information on the RC-1 Rock Crusher.  This crusher will reduce 1″ gravel to 1/8″ in a single pass. It is easy to pour the grind through the machine again for a second and third pass to achieve 120 mesh powder suitable for mixing into soil

rock dust biochar
Portable RC-1 Gravel Rock Crusher with Cart and 5 gallon bucket

About Rock Dust

Doing my own research on the web with respect to Rock Dust I have found pros and cons on the subject.  Generally those that put time and effort into learning how to use rock dust, have great success.  Those that are impatient and  just sprinkle it on the garden or haphazardly apply it generally fail to achieve any good result.

I find from my searching that organic soils with higher amounts of compost, generally see plants with better mineral uptake.  Mineral rich plants are more draught, disease and pest resistant.  In the end, the plants are more nutritious.  These people have many years of trial and error testing to build their knowledge base.


On the other hand, there are those that dismiss the value of rock dust.

  1. One web site discusses the cons in an organized way but focuses on two things. One is a video of a home gardener that just added rock dust and looked at the results and concluded it didn’t work.  Those that have had good success have gone a bit further than just sprinkling it on the garden in different amounts.
  2. The other is the statement that decomposition of rock takes over 100 years and therefore rock dust is useless and a waste of money.

Decomposition of rock is generally the grinding or weathering into finer and finer particles to a point of becoming useful to a variety of organisms from bacteria to fungus or anything else that would use it.   Some plants grow on rocks with little soil.

Rock Dust Contributes to the Vibrance of Garden Plants

With not much reading one can conclude that with proper application rock dust contributes to the vibrance of garden plants. However, proper application seems to be to mix the rock dust first with compost that has active bacteria in it and let it do its work.  The bacteria works the composting and breakdown of the rock dust.  Then you mix the compost/rock dust with good bio char and then add this to the soil.

Different Types of Rock Dust

There are two basic types of Rock Dust – Granite and Basalt

  • Granite – glacial dust less uniform in its mineral makeup.  Grinding river cobbles produces fine powder.
  • Basalt is alkaline and has better uniformity in trace minerals.  Basalt rock dust is the Gold standard for remineralization.

Three Vital Components for Good Soil

The thee vital components to good rich soil are

  1. Rock Dust is one of three vital ingredients to a flourishing garden.
  2. The second is bio char, a charcoal component that adds lots of surface area for bacteria.
  3. The third is bacteria rich composite.

One can easily reach the conclusion that Rock Dust plus Bio-char in a Compost rich soil will enhance the soil for a flourishing garden.

A good overview of the vital ingredients in a garden can be found in this video by John of Growing Your Greens.  He does a great interview with a Vermont Gardener on Rock Dust and other vital nutrients for vibrant garden.  In summary mineral rich plants are more draught, disease and pest resistant.  In the end, the plants are more nutritious.

Before Using Rock Dust Compost it to Activate it

In is important to put rock dust into compost first to increase nutrient density.  Mix rock dust first with compost first to prevent the microbes from digesting the minerals with less emphasis on composting. To Activate Rock dust mix it with fresh plant cutting and let it composite.   Here is a good article on Activating Rock Dust 

Here is some information directly from Grow 

The Result of Adding Rock Dust Add to My Soil

Adding rock dust to the soil adds trace minerals and micronutrients.  In addition, it Increases the Cation Exchange Capacity, or CEC, of your soil.

As a result this feeds the beneficial microbes that live in your soil.

Basalt Rock Dust

Basalt Rock Dust is made of the volcanic rock called basalt.  Some gardeners prefer basalt because of the risk of heavy metal contamination in other products.  As a result Basalt rock dust contains a more limited variety of minerals than the others.  It is an excellent source for calcium, magnesium, iron, manganese, silicon, cobalt, zinc, boron, and aluminum.

Glacial Rock Dust

Glacial Rock Dust as the name says, is made from rocks deposited by glacial action. It is made of a wide variety of rocks, and contains a complex blend of minerals. It is good for adding calcium, iron, magnesium, and potassium with traces of manganese, cobalt, silicon, and small amounts of other minerals.

Enhancing Gardens with Rock Dust Can be Costly.

One of the biggest costs for enhancing garden soils with rock dust is the cost.  Ranging from $1 to $10 a pound the cost for applying rock dust to a small garden can be costly.   You can now purchase an inexpensive rock crusher and bring home the river gravel or volcanic rocks and make your own rock dust.  Within a short time you will pay for your rock crusher.

See the RC-1 Portable Rock Crusher here.

For more information on rock crushers contact Cat 6 Tools, LLC


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