Description
The Grodan Gro-Block Improved Hugo 6" with hole is the current-generation 6 inch rockwool block. 6 x 6 x 5.8 inches, sold as singles, with a pre-formed hole for a propagation cube.
This is the size most growers finish in, and the Improved wool is where Grodan put their research. UK and EU stock.
What "Improved" actually changes
Grodan worked with Wageningen University in the Netherlands and with commercial growers in North America to re-engineer the wool structure and the wetting agent. Three things come out of it that you can feel in the room:
- Faster rooting-in – the optimised fibre structure lets roots take hold sooner after transplant.
- Even water and EC through the whole block – not just across the block but over its height, which matters more on a 6 inch than anywhere else in the range, because that is where the top-to-bottom gradient usually shows up.
- Holds its shape – structure, firmness and rigidity stay put across a full cycle instead of slumping under a heavy plant after repeated wet and dry.
The advanced wetting agent and hydrophilic treatment are the reason it re-saturates so evenly, which in turn means less water and less nutrient wasted getting the block back to where you want it.
Wetting instructions
The Improved blocks have their own preparation procedure, which is not the same as the 24 hour soak used on standard rockwool. Grodan's wetting instructions for Improved Gro-Blocks (PDF). Follow those rather than the generic advice.
Improved Hugo or the standard 6 inch Hugo?
| Improved Hugo 6" (this product) | Standard Grodan 6" Hugo | |
|---|---|---|
| Size | 6 x 6 x 5.8" | 150 x 150 x 140mm |
| Hole | Pre-formed | 36mm |
| Wetting agent | Grodan Advanced | Standard |
| Preparation | Follow Grodan's Improved wetting PDF | 24 hour soak at pH 5.5 |
| Sold as | Singles | Singles |
| Best for | Crop steering, tight EC control | Straightforward veg to harvest |
Which rockwool size do I need?
Rockwool works as a ladder. You start small and pot on into the next size up, each time without disturbing the roots. Here is the full range we stock and where each one sits.
| Product | Size | Where it fits | Takes |
|---|---|---|---|
| Grodan Propagation Cubes | 25mm or 36mm | Seed and cutting | Bare cutting or seed |
| Cultiwool Loose Mini Cubes | 10mm, 90L or 200L | Loose fill, any pot | Fills pots and trays |
| Cultiwool Mapito | 80L bag | Loose fill, any pot | Fills pots and trays |
| Grodan Block 3" | 7.5cm | First pot-on | 2.5cm or 3.6cm hole |
| Grodan Improved GR4 3" | 3 x 3 x 2.5" | First pot-on | Pre-formed hole |
| Grodan Block 4" | 10cm | Veg | 2.5cm or 3.6cm hole |
| Grodan Improved GR10 4" | 4 x 4 x 3.1" | Veg | Pre-formed hole |
| Grodan 6" Hugo Block | 150 x 150 x 140mm | Veg to harvest | 36mm hole |
| Grodan 6" Hugo, dripper hole | 150 x 150 x 140mm | Veg to harvest | 36mm hole plus dripper hole |
| Grodan Improved Hugo 6" (this product) | 6 x 6 x 5.8" | Veg to harvest | Pre-formed hole |
| Cultiwool 8" Big Daddy Block | 20 x 20 x 19.5cm | Full cycle, large plants | Takes an 8" cap |
| Cultiwool 25cm X-Fibre Mini Slab | 25.2 x 19.5 x 7.5cm | Under a block, full cycle | One 6" or 8" block sits on top |
| Grodan Vital Slab 1m | 100 x 15 x 7.5cm | Multi-plant, full cycle | Three to four blocks |
| Grodan Vital Slab 1.3m | 130 x 15 x 7.5cm | Multi-plant, full cycle | Four to five blocks |
Sizes are nominal. Blocks are sold as singles or in strips depending on the line.
Goes well with
- Grodan Improved GR10 4" – The rung below in the same Improved range, so the wool behaves the same way.
- Cultiwool 25cm X-Fibre Mini Slab – A 6" block sits on one of these for extra root mass and a bigger buffer.
- FloraFlex 12 Plant Bubbler System for 6" Rockwool – Feeds twelve 6" blocks evenly in a 4 x 4ft space.
- Grodan Propagation Cubes – What goes in the hole.
Frequently asked questions
Do I prepare these the same as normal rockwool?
No. The Improved range has its own wetting procedure because of the advanced wetting agent. Use Grodan's Improved Gro-Block instructions, not the generic 24 hour soak.
Is it worth paying more than the standard Hugo?
If you are crop steering and watching EC and water content closely, yes, because the even distribution over the height of the block is what you are paying for and a 6 inch is where that gradient bites. If you are growing straightforwardly from transplant to harvest, the standard Hugo does that job well.
Do I need a slab underneath?
Not necessarily. A 6" block on its own will take most crops to harvest. Put it on a mini slab or a Vital slab when you want a bigger buffer between feeds or a heavier plant to stay upright.
How do I feed them?
Little and often at pH 5.5 to 5.8, aiming for 10 to 30 percent run-off. Most growers run a dripper per block. See Dripper Systems, Run to Waste Systems and pH & EC Meters.
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Rockwool · Growing Media · Dripper Systems · Run to Waste Systems · Grow Room Irrigation
