Product Information

Grodan Granulate 25 kg Fine is a premium loose stone wool (rockwool) substrate designed for professional and hobby growers seeking superior water retention, excellent aeration, and consistent plant performance in hydroponic, soilless, and container growing systems.

Made from high-quality molten basalt rock and limestone, spun into fine, hydrophilic fibres, this ultra-clean and sterile granulate provides an inert, pH-neutral growing medium that gives precise control over nutrient delivery and root zone conditions. It offers outstanding moisture buffering while maintaining optimal oxygen levels around the roots—ideal for water-hungry crops or plants that demand uniform hydration.

Key Benefits:
Exceptional water-holding capacity with rapid re-wetting properties
Superior aeration to promote healthy root development and prevent compaction
Sterile and pathogen-free—no risk of soil-borne diseases
Versatile usage: perfect as a standalone medium in pots, containers, hanging baskets, or raised beds; excellent when mixed with perlite, expanded clay, coco coir, or peat-based substrates to boost moisture retention and improve structure
Supports both recirculating and run-to-waste hydroponic systems
Lightweight and easy to handle in the 25 kg bag (yields approximately 150–170 litres of high-quality usable substrate)

This fine granulate (shorter fibre length) delivers a stable structure with enhanced water absorption, making it especially effective for precision growing and custom substrate mixes.

Always pre-soak and condition rockwool (it starts slightly alkaline, ~pH 8) in pH-adjusted water (~5.5) before planting for best results.