Rockwool is an excellent material to use when cloning and growing plants, as it does not degrade over time and remains sterile – this helps protect cuttings from bacteria or fungus infiltration.
Prep your cuttings by dipping the cut end in rooting hormone and placing them into a nursery tray equipped with a humidity dome.
The Process
Rockwool first gained popularity as insulation in the 70s before being proven successful as a growing medium in horticulture. A man-made substrate guaranteed sterile and free from any weed seeds, bugs or diseases makes rockwool ideal for hydroponic cultivation and its quality is consistent throughout its use, which makes it particularly advantageous in commercial settings.
Basalt rocks are crushed and liquified at high temperatures in a furnace to produce mineral wool that resembles steel wool in appearance and texture. Once this material has been processed into long, thin fibers it’s then spun and bound together using binding solutions, creating an easily drainable growing medium with large openings to promote root formation.
Rockwool cubes are then formed out of this product and cut to various sizes for use by plants, with 1.5″ cubes being most often utilized for germinating seeds and propagating cuttings, while larger 2.5″ cubes may also be found in commercial grow operations. As opposed to other hydroponic growing media such as peat moss or coco peat, rockwool does not contain natural nutrients so must be soaked in a pH balanced solution in order for plants to use it effectively.
Squeezing rockwool cubes when soaking is best avoided as this compacts their internal structures, decreasing water-holding capacity and restricting oxygen flow through the substrate. Once ready to be used, they should be stored in a seed starter tray equipped with humidity domes in order to maintain proper moisture levels and promote germination.
Once a plant is established in a rockwool cube, it requires regular misting with hydroponic nutrient solution to ensure proper absorption by its substrate. A pH test strip should be used prior to irrigation for monitoring. Furthermore, acidic water should be added periodically in order to maintain an ideal range for your crop’s ideal pH levels.
Due to rockwool being non-biodegradable material, it will take years for it to break down in landfills; therefore it’s essential that when finished with using it for gardening purposes you dispose of it responsibly. You could either add it into compost piles or mix into soil for added nutrients and organic matter but no matter the method or use you use rockwool must not simply end up going into the trash cans! If growing within rockwool this is even more critical.
The Raw Materials
Rockwool is created using a mixture of various rock (silicon oxides) components which are heated at high temperatures until they melt together like cotton candy, creating a solid block-shaped mass which is later “bonded” with resins for finished products like blocks, slabs and plugs sold at home improvement stores. Roughly 97% by volume of the final product contains airspace resulting in very light yet porous rockwool products.
Rockwool is widely considered an ideal substrate for hydroponic applications due to its inert nature, providing the optimal balance between water holding capacity and air space for root development. When properly hydrated, rockwool offers increased control over nutrient feeding schedules between vegetative and generative growth phases without fear of drastic fluctuations in either EC or pH levels.
Rockwool production begins by melting raw materials at very high temperatures in a furnace, before being passed over specialized spinning machines known as spinners and then being blown across long specialized spinning strands known as “spinners,” whereby it dissipates into long mineral wool filaments which can then be collected and stretched until thick enough to mold into insulation mats and then cut down to standard-sized batts for shipping out to retailers.
Rockwool can also be purchased as loose fiber, commonly referred to as “flock.” This form is popularly used for horticultural applications as its thinner size makes it suitable for hydroponic systems with frequent washing required and possible losses in pore structure over time. Smelted rock wool from flock is similarly used, however the resultant product requires much thinner rock wool than its solid forms like plugs, blocks or slabs. Flocks must still undergo the smelting process but results in much thinner rock wool products than its solid counterparts (plugs, blocks and slabs). They must also undergo the melting process just like the solid products (plugs blocks and slabs), yet require much thinner rockwool than its solid counterparts (plugs blocks and slabs). Flocks may lose some pore structure over time due to frequent washing required of washing with hydroponic systems which may result in losses from their use over time as compared with plugs blocks bonded counterparts bonded counterparts which allow more frequent washing processes.
ROXUL’s rockwool solutions are used widely for soundproofing commercial buildings, as it provides an effective means of reducing noise levels in office spaces, shopping centers and industrial complexes. Because this material can be tailored specifically to each space’s noise reduction requirements – no surprise then that ROXUL is considered the world leader when it comes to stone wool solutions! With manufacturing facilities located worldwide.
The Manufacturing Process
Rockwool insulation products are manufactured as an insulation product that are generally considered safe to use in construction industries. Starting mix is heated and fed through large spinning chambers designed to stretch it into long wool-like fibers before being bundled together to form rockwool products found in stores or utilized by hydroponic growers.
Rockwool manufactured during its manufacturing process is completely sterile and does not contain any bacteria or fungus that could interfere with plant growth, making it an excellent choice for propagation techniques that require an innocuous, bacteria-free environment. Rockwool can also be used successfully when combined with hydroponic nutrients and equipment for cultivation of most vegetable and herb crops.
Horticultural grade rockwool differs significantly from its thermal insulation counterpart due to the nature of its raw materials; it primarily features volcanic rock materials which can be altered to suit specific growing needs by making changes to the manufacturing process, supporting and encouraging plant growth through various means. Because of these differences in raw material composition, handling and storage of this horticultural variety must differ significantly than for its thermal counterpart.
Before using rockwool as a growing substrate, growers should first leach it in acidic water. This will remove any lime buildup on its surface caused by production, as well as lower its pH for optimal growing results.
Once leached, rockwool can be integrated into various hydroponic systems including NFT, Water Table and Ebb & Flood hydroponic systems designed specifically for growing crops. When selecting rockwool products such as slab, block BAB-12 or granulated rockwool products for these systems it is imperative that they use appropriate sizes (slab/block, BAB-12 granulation or otherwise).
Horticultural and thermal versions of rockwool differ in that both require short, frequent applications of nutrient solution for optimal results. This ensures the rockwool doesn’t dry out and that roots have constant access to moisture sources; particularly important when working with NFT and Water Table types of systems. Once applied, excess must be allowed to drain freely so as to avoid over watering issues.
The End Product
Rockwool is a manmade substrate that can serve multiple functions. Insulation forms of it can often be found in homes and commercial buildings where it provides soundproofing benefits; or alternatively it can serve as hydroponic growing medium.
Mineral wool fiber can be formed into this material by layering long strands together and melting them through heat treatment to form the substrate, which then can be formed into different shapes such as cubes for plant propagation or larger slabs for insulation of walls or equipment.
Once complete, rockwool substrate is highly durable and long-term. Additionally, it provides effective insulation properties, and boasts excellent moisture retention properties; meaning that water remains within it longer than other growing medias; however, this may lead to overwatering so it is crucial that soil moisture levels be carefully monitored.
Rockwool can provide many advantages for propagation, including being free from bacteria or fungus that could impede plant growth. Furthermore, its lightweight construction makes it easy to handle and transport; making it ideal for growing in small spaces or mobile systems.
Rockwool should be soaked in acidic water to lower its pH before use; this will prevent lime buildup which could otherwise cause seedling roots to rot. Distilled water would be ideal, although tap water may suffice in an emergency. Once ready for planting or propagation trays can then be placed onto rockwool for growth.
One key thing to keep in mind when working with rockwool is its difficulty in being cut accurately, so wearing protective gloves and eye protection when handling the substrate is always recommended. Furthermore, its wet form should always be avoided due to its sharp fibers which could potentially irritate both your skin and lungs.
