Grodan Improved Gro-Block | 6in - Jumbo - 6in x 6in x 4in - Pre-Cut Holes

Wide-Footprint Stonewool Block for Established Root Systems, 6in Jumbo

Some vegetative plants develop a wider root spread before they need much more vertical depth, which calls for a block shaped to match that spread rather than a taller cube. Grodan's Jumbo block, at 6in x 6in x 4in, gives that wider, shallower profile in the same engineered stonewool fiber used across Grodan's GR-series, with a pre-cut hole for a smaller rooted block.

At 6in x 6in x 4in, the Jumbo's flatter profile suits growers whose bench height or irrigation setup favors a wider block over a taller one like the Hugo cube.

Key Features & Benefits

• 6in x 6in x 4in Format — a wider, shallower profile than a cube-shaped block of the same footprint.
• Pre-Cut Hole — sized to receive a smaller rooted Gro-Block for continued root development.
• Hydrophilic Fiber Structure — manages water and air distribution across the block's wider surface area.
• Loose Carton Packaging — ships ready for placement without additional handling.

Who Should Use the Jumbo Gro-Block

Growers whose bench height or irrigation layout favors a wider, shallower block over a taller cube, while still needing a larger stonewool volume than a propagation-stage block, are the fit for Jumbo.

About Grodan

Grodan introduced engineered stonewool growing media in 1969 and, as part of ROCKWOOL Group, continues to offer that fiber technology across different block shapes, including the wider-footprint Jumbo format.

Frequently Asked Questions

How is the Jumbo block different from the Hugo cube?

Jumbo measures 6in x 6in x 4in, giving it a wider, shallower profile than the 6in x 6in x 6in Hugo cube. Growers pick between the two based on bench height, irrigation setup, or how much vertical root depth a crop needs.

When should I move a plant into a Jumbo block?

Move a plant into a Jumbo block once it needs more stonewool volume than a propagation-stage block provides, but a wider, flatter profile suits the bench better than a taller cube. That transition typically happens once roots have filled the smaller starter block.

How do I prepare a Jumbo block before transplanting?

Pre-soak it with pH-adjusted water, then insert the smaller rooted block into the pre-cut hole so roots grow down and out into the Jumbo's wider volume. Keep the block evenly moist through the first several days after transplant.

Does the Jumbo block use the same stonewool as other Gro-Blocks?

Yes, it's manufactured from the same engineered hydrophilic fiber used across Grodan's GR-series; only the block's external dimensions differ. That shared fiber base means water and air move through Jumbo the same way they do in Grodan's other block sizes.