Grodan 75mm Rockwool Cubes No Hole, Pack of 6. Large Hydroponic Propagation Blocks Australia

The Large-Format Rockwool Block for Advanced Propagation, Cloning and Transplant-Ready Root Systems

When cuttings outgrow a 40mm starter cube or you need more root zone volume from the start, the Grodan 75mm x 75mm No Hole Rockwool Cube is the commercial-standard step up. A larger root zone, the same sterile stone wool structure, and a no-hole design that gives you full control over cutting placement, seed depth, and plug insertion.

Used in professional greenhouse and hydroponic production worldwide, the 75mm cube is the transplant-ready format — the final propagation stage before plants move into their main growing system.

Why the 75mm No Hole Format Outperforms Smaller Cubes at This Stage

• Expanded Root Zone Volume. Nearly four times the root space of a 40mm cube. Supports larger cuttings, longer propagation cycles, and plants that need more establishment time before transplanting.
• No Pre-Drilled Hole Design. Customise insertion point, depth, and angle for large cuttings, multi-stem propagation, or transplanting rooted 40mm plugs directly into the 75mm block.
• High Air-to-Water Ratio. Stone wool fibre structure maintains oxygen availability at the root zone even when fully saturated, preventing anaerobic conditions and root rot during extended propagation periods.
• Sterile Stone Wool Medium. Inert mineral fibre with no organic matter to harbour pathogens or competing biology. Consistent contamination control across a full propagation tray.
• Superior Water Retention and Drainage Balance. Holds moisture evenly without waterlogging, providing stable hydration to developing roots through the full vegetative establishment phase.
• Uniform Fibre Structure. Encourages aggressive, even root expansion through the block, producing a dense root ball that transplants cleanly into slabs, pots, or recirculating systems.

Technical Specifications

• Dimensions: 75mm x 75mm
• Material: Rockwool (mineral stone fibre)
• Design: No pre-drilled hole
• Structure: High-porosity fibre matrix
• Sterility: Sterile growing medium
• Water Retention: High, with drainage balance
• Aeration: High oxygen root zone
• Origin: Netherlands (Grodan manufacturing)

How to Use Grodan 75mm No Hole Cubes

• Pre-soak cubes in pH 5.5-5.8 water for 30-60 minutes before use. Add Nefarious Rhizo Tonic to your pre-soak solution at the recommended rate to prime the cube with root-stimulating compounds before insertion. Do not squeeze — allow to drain naturally to maintain fibre structure.
• Cuttings: Use a clean blade or skewer to create your insertion point at the desired depth and angle. Apply Clonex Rooting Gel to the cut stem before inserting.
• Transplanting from 40mm cubes: Cut or press a recess into the 75mm block to accept the rooted 40mm cube directly. Roots will grow through into the larger block within days.
• Transplanting to main system: Move when roots are visible at the base and sides of the block. Transplant the cube directly — do not remove it from the root ball.

Grodan Rockwool Propagation Range

Structure your propagation system across the full Grodan cube range for maximum efficiency.

• Grodan 40mm Rockwool Cubes — seed germination and early clone rooting stage
• Grodan 75mm No Hole Cubes — advanced propagation, large cuttings, and transplant-ready root development

Frequently Bought Together

• Clonex Rooting Hormone Gel. Apply to cuttings before inserting into the 75mm block for faster, more reliable root initiation.
• Nefarious Rhizo Tonic. Add to your pre-soak solution to prime cubes with root-stimulating compounds before use.
• JB's Propagation Lid. Self-dripping humidity dome that maintains the high-humidity environment large cuttings need during the rooting period.
• HOMEbox R80S Propagation Tent. Dedicated propagation environment for full climate control over temperature and humidity during cloning and establishment.
• X-Stream Aeroponic Cloner. For growers running aeroponic propagation systems alongside rockwool-based setups.

Product Details

• Type: Large-Format Stone Wool Propagation Block
• Dimensions: 75mm x 75mm
• Design: No pre-drilled hole
• Application: Advanced cloning, vegetative growth, transplanting
• Compatible Systems: Hydroponics, DWC, coco, greenhouse production
• Pre-Treatment: Pre-soak at pH 5.5-5.8 before use
• Vendor: Grodan