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