Talk to any seasoned commercial cannabis cultivation consultant and they will tell you the same thing: when it comes to planning a cannabis growing facility from scratch, choosing your growing medium should be a top priority. What may seem like a minor detail or even an afterthought to the uninitiated actually has far-reaching consequences further down the line, potentially impacting many other decisions regarding cultivation facility design and attendant standard
Your chosen growth media could well influence the type of benching you install; it will also greatly influence your regime of nutrients and additives, as well as overall irrigation strategy and design. What’s more, your preferred substrate or soilless potting mix will affect how you approach waste management and recycling. Last but definitely not least, this crucial decision will dictate the future feasibility of recirculating your run-off / leachate nutrient solution, potentially unlocking huge reductions in fresh water and fertilizer use—or not!
This information might be all well and good for those just starting out—but it also raises an important question for the rest of us: is it too late for cultivation facility managers to consider switching growing media or trialing a new hydroponic substrate in their licensed growing operation? Fortunately, the answer is ‘no’. Commercial cannabis cultivators who are considering a switch to stone wool for improved crop management and sustainability have many options available when it comes to evolving and improving the efficiency and productivity of their growing facility.
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The Benefits of Switching to Stone Wool
Stone wool growers use less water and nutrients. Stone wool (also known as ‘rock wool’ or ‘rockwool’) has a unique microporous structure replete with tiny pores and inter-fiber spaces. This gives stone wool a truly unique ability to retain water and air simultaneously—the perfect environment for plant roots, reducing overall consumption and costs. No wonder that stone wool is a mainstay of commercial agriculture!
Stone wool growers enjoy more efficient and precise management over water and nutrients within the root zones of their plants. The pores in the stone wool are small enough to hold substantial amounts of water by capillary action, yet large enough to allow excess water to drain away, preventing waterlogging and promoting healthy root oxygenation. This special balance is the magic behind the legendary plant growth in stone wool, especially in controlled environment agriculture where precision is crucial.
Cultivators enjoy greater control and consistency from crop to crop. Stone wool blocks and slabs provide uniform conditions for every plant you grow. This leads to consistent plant growth and beautifully even canopies that are easier to illuminate efficiently. Workers don’t need to spend time filling containers or tapping them down to eliminate air pockets leading to much higher productivity when it comes to transplanting.
There’s much less dust and debris and zero contaminants! Stone wool products are created by heating basalt rock up to high temperatures—high enough so that it becomes molten and can be spun into fibers. This process eliminates organic contamination problems that can plague growers, resulting in a clean, pathogen-free growing media right from production. Growers using coco coir, peat and soil-based potting mixes cannot enjoy anywhere near the same peace of mind as these potting mixes are well-known to sometimes harbor pests and pathogens. Cultivation facilities using stone wool enjoy a much cleaner environment with far less dust generated from growing media.
Stone wool unlocks nutrient recirculation. Stone wool is pathogen-free at the point of production, with virtually no cation exchange capacity. This means it can hold on to nutrients without chemically interacting with them. Stone wool also doesn’t dump particulates into run-off. Instead of running to waste, cultivators can channel leacheate nutrient solution back into reservoirs to be re-used, massively cutting down on fresh water and nutrient usage.
Ease of Monitoring and Control. Grodan offers technological tools like the GroSens Suite rootzone monitoring software and sensors that are specially designed for use in stone wool to optimize growing conditions and outputs .
Practical Steps for Testing and Transition to Stone Wool
Start Small: It makes sense to begin using stone wool in your propagation room and compare its performance with your existing propagation plugs or substrates. Even within this sub-category, Grodan offers many options.
Implement a Phased Transition Strategy: Once you’ve seen for yourself the efficacy of stone wool in your propagation room, it will probably seem quite natural to start integrating it into your vegetative growth chambers. Cuttings vegged up in 3” or 4” grow blocks can still be easily and seamlessly transplanted into final stage containers filled with your existing soilless mix, or you could try one of Grodan’s loose fill media options to fill your pots instead, such as Grodan granulate (aka ‘rockwool flock’) or Grodan Growcubes (aka ‘croutons’).
Don’t Forget the Economic Considerations
During your transition to stone wool, it’s important to recognize the associated cost savings resulting from reduced water and nutrient usage. There’s also the return on investment through higher yields and lower operational costs, supported by case studies or testimonials from existing Grodan users .
So, What's the Next Step?
Ready to experience the benefits of Grodan stone wool? Contact us to request a trial and join our mailing list—we’re here to support your upgrade to stone wool every step of the way!
