Rockwool

What is rock wool, and why is it used in cannabis cultivation?

Rock wool is an artificial substrate of mineral origin, made from volcanic rock subjected to high temperatures until it becomes fibers. These fibers, grouped into blocks, plugs, or slabs, provide a very porous, lightweight, and airy growing medium. Its use is especially common in hydroponic systems and during germination or cloning phases, where very fine control of the root environment is required.

Main applications of rock wool

This material is primarily used for germinating seeds, rooting cuttings, and growing in soilless systems such as NFT, DWC, or automated irrigation systems. Thanks to its ability to retain water while providing excellent oxygenation, rockwool allows for faster growth, improved root development, and more efficient nutrient uptake.

What type of grower is it ideal for?

Rockwool is perfect for growers looking to control all growing parameters, especially in hydroponic systems. It's also very useful for those who take clones frequently, as it maintains stable humidity and promotes rapid rooting. Although it requires a little more technique than other substrates, its benefits are highly valued by experienced growers or those looking to professionalize their system.

Benefits compared to other substrates

Rockwool contains no nutrients, allowing for precise adjustments to watering and fertilization. It doesn't compact or degrade easily, ensuring constant aeration throughout the growing season. It's also very clean, lightweight, and easy to handle. Thanks to its porosity, it provides an ideal environment for the development of healthy roots, resulting in stronger, more productive plants.

What formats exist, and how to choose the right one?

At Alchimia, you have different formats depending on the cultivation phase:

• Rock wool plugs: such as Grodan or Cultilene, are perfect for germination or cuttings.
• Blocks: ideal for transplanting from plugs and maintaining vegetative growth.
• Slabs or plates: recommended for complete crops in hydroponic or automated systems.

Some products come with pre-drilled holes to facilitate transplanting or inserting cuttings, while others require a little preparation. It's important to hydrate the wool well before use and adjust its pH to prevent blockages in nutrient absorption.

Featured brands and products

Among the most recommended products are Grodan Delta plugs and Cultilene blocks, both recognized for their quality, stability, and ease of use. Complete rock wool slabs are also available for professional installations or large-scale grows.

Frequently asked questions about rock wool for cannabis cultivation

Should the pH be adjusted before using rock wool?

Yes, it is recommended to hydrate the wool with water adjusted to a pH between 5.5 and 6.0 to avoid nutritional blockages and ensure proper absorption from the start.

Can rock wool be reused?

It's not ideal. Although it's possible to disinfect it, its structure can degrade and accumulate salts, so it's recommended to use it only once to avoid the risk of disease or imbalances.