Why You Should Be Using Stonewool Grow Media?

Posted on June 15, 2020 by Red Rock Block

Stonewool Grow Blocks: The Revolution of Grow Media for Commercial Greenhouses, Indoor Farms, and CEA or Hydroponic Facilities

In all aspects of the horticulture production industry, both small and large scale operations are making positive upgrades to better grow technologies and best practices to reduce their footprint and inputs, while not sacrificing their outputs and yields. One of those implementations focuses on the hydroponic growing process through the use of commercial-grade stonewool grow media products. There are many benefits that make this particular type of grow media the best solution for growers.

What is stonewool?

Stone wool is a natural product that originates from an extremely caustic source- molten rock. The molten rock is carefully spun and woven into various shapes and sizes for the use in many applications. At first, stonewool was used in the construction industry due to its ability as an excellent insulation material. In the 1970’s the horticulture industry conducted research to see the possibility of using the product for the growing industry. They found that this material is an excellent material to use and has grown in use and popularity ever since. The benefits range from durability, better use of resources, ease of use, operational efficiency, and much more.

Characteristics of Stone Wool?

The way that the molten rock is spun and stacked will determine the properties of the growing material. These properties range from moisture holding capacity, aeration or porosity, and pH. One version of stone wool for example can maintain a drier root zone to help crops from being overly green or having excessive vegetative growth. While another is designed for quick root growth and development. The diversity of the different stone wool products allows a grower to choose and design their materials that meet the specific individual needs of their growing operation and crops.


Stonewool is a product that can be used over many growing seasons. Unlike other materials used in a hydroponic system, stone wool has the ability to withstand the wet, hot, and bright environment of a greenhouse. Because stone wool is made up of basalt rock that has been melted and spun, the material does not decompose. This is an excellent option for the grower that does not want to worry about restocking for every growing cycle or season.

Plant/Crop Nutrients and pH Control

Stone wool is a natural product that is neutral. Due to the material it is made from, stone wool once rinsed has a neutral pH and does not harbor pests and pathogens. Other growing media such as coco coir can house pests and possible pathogens once in storage in the greenhouse. This material is the best to start with a clean slate without worrying about balancing the plant nutrients and pH.


Stonewool grow media come in all shapes and sizes, as well as, have the ability to be installed into larger blocks and slabs-a.k.a.- “blocking up”. Each size of stone wool block or slab has a specific purpose. The smaller stonewool starter blocks or stonewool plugs are used to start seedlings and establish growth and root development. The blocks or slabs are used to allow for deeper root growth and better support of the plant as it develops and grows. These versatile materials can be cut and customized specific to just about any type of commercial grow operation. With ease of transplanting, customizable shapes, sizes, and spacings, as well as neutral growing area and low breakdown of materials, it is no surprise that this material has become one of the most popular growing mediums for the horticulture industry.

Click here for more information about RedRock Block’s stonewool starter blocks, grow blocks, grow cubes, grow slabs, and grow plugs

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