“Growers can save money reusing rockwool slabs”

“Recycling used rockwool slabs isn’t popular,” admits Pius Floris of Plant Health Care.” Mostly because people fear infections. Which of course is perfectly understandable; we have been taught that the nursery must be cleaner than a hospital. But averting all bacteria might not be the solution. Scientific research shows that super clean has the opposite effect. In hospitals, people know that the most resilient bacteria can be controlled by cleaning less, not more.”

 

This may seem counterintuitive, but according to Floris it makes sense. “This way, harmless bacteria are able to increase and limit the advance of more harmful bacteria. Plus, many malicious fungi and bacteria tend to become resistant, requiring more and more aggressive means. It’s a costly process. The horticultural sector claims it is environment-friendly these days; that means you can’t keep reverting to chemicals. My point is: this kind of relentless cleaning isn’t necessary anymore. Our knowledge has reached a point where we know that natural means are at least as reliable as chemicals.”

One of the means Floris advocates is the reuse of Rockwool substrates. “Older ones contain lots of organic waste that can be used as fertilizer for new plants. So keeping the substrates doesn’t just save money and effort, is can benefit new growth. By applying two kilos Plus Compete per hectare of Rockwool, one week before planting, you allow the right bacteria to settle. They become incalculable quantities and will utilize every nook and cranny of the old substrate, effectively cutting off the increase of possible pathogens. The same bacteria in Compete Plus stimulate the development of new roots, helping the absorption of minerals, and calcium is better absorbed into the plants. By repeating this process during cultivation once every month your old rugs will perform better than you ever thought possible."