What is rock wool?
Rock wool, also known as Rockwool, is an inorganic substrate made from molten volcanic rock, processed into fibers at high temperatures.
Widely used in the building insulation sector, rock wool has found an important application in agriculture, particularly in hydroponic systems (i.e. on neutral soil). It comes in the form of cubes, blocks and plates and provides a certain stability and porosity to root development.
Its physical properties, including high water retention and drainage capacity, make it an excellent choice for crops that require precise hydration and nutrient management, such as cannabis cultivation, but also tomatoes, cucumbers and peppers.
This substrate is chemically inert, allowing rigorous control of pH and nutrient concentrations in hydroponic solutions.
Rock wool: what is the point in cannabis cultivation?
Rock wool has several major advantages in growing cannabis, especially in hydroponics.
Its ability to maintain a perfect balance between water retention and aeration allows for optimal root development, which is simply DECISIVE for vigorous and productive plants.
This inorganic substrate therefore ensures a certain chemical stability by preventing variations in pH from affecting the absorption of nutrients by the cannabis plant. With this well-oxygenated root environment, rock wool minimizes the risk of root asphyxiation and promotes rapid and homogeneous growth of cannabis plants.
Also note that its fibrous structure allows excellent drainage to reduce the risk of root rot and facilitate watering management.The reusability of rock wool, after sterilization, in fact also an economical choice for professional cannabis growers.
Farmers also appreciate its compatibility with hydroponic systems, from drip cultivation to NFT (Nutrient Film Technique) systems and flood irrigation.
Finally, rock wool facilitates the control of the different variables of the growing environment and therefore makes it possible to maximize the yields and quality of cannabis flowers (concentration of non-psychotropic cannabinoids and terpenes).
How do cannabis growers prepare rockwool before use?
The management of rock wool in hydroponics requires special attention to maximize the benefits of this substrate. It must be prepared according to the rules of the art, in particular by immersing it in a buffer solution to adjust its pH, often slightly alkaline at the start. This step guarantees a neutral environment for the roots.
During cultivation, irrigation control is essential. Rockwool effectively retains water while providing good drainage, but overwatering can lead to saturation and a lack of oxygen to the roots. It is therefore necessary to carefully monitor the humidity level of the substrate and adjust the watering cycles accordingly.
Attention: rock wool does not provide any nutrients to plants. All nutrients must be supplied via the hydroponic solution, which requires constant and careful monitoring of macro and micronutrient levels to avoid deficiencies or excesses.
After harvest, rockwool can be reused, but it must first be sterilized to remove pathogensand root residue. This operation extends the life of the substrate and maintains a healthy environment for subsequent cannabis crops.
