Description
The Cultiwool 25cm X-Fibre Mini Slab is a single-plant rockwool slab. 25.2 x 19.5 x 7.5cm, sized so that one 6" or 8" block stands on top of it, giving the plant a much bigger reservoir without committing to a full 1m or 1.3m slab and a shared feed line.
That is the reason to buy one. On a long slab every plant in the row shares the same water content and the same EC. On a mini slab each plant gets its own, so you can steer them individually and pull one without disturbing the rest.
Why growers use them
- Per-plant control – one slab, one plant, one set of numbers.
- Supports a full lifecycle – enough root room to carry a large plant from transplant to harvest.
- Physical stability – the extra mass underneath keeps a top-heavy plant upright.
- Algae and root pest protection – the resistant cover keeps light off the wool.
- Re-saturates evenly – water content and EC distribute uniformly through the slab, which is what makes a crop steering strategy repeatable rather than a guess.
Specification
| Slab dimensions | L25.2 x W19.5 x H7.5cm |
| Material | Cultiwool X-Fibre stone wool, inert and pH neutral |
| Cover | Light-blocking resistant wrap |
| Takes | One 6" or 8" block on top |
| Pre-soak pH | 5.5 to 5.8 before use |
Before you use them
Rockwool leaves the factory with a naturally high pH, so it has to be conditioned before anything goes on it. Soak for 24 hours in a weak nutrient solution under 1.0 EC, adjusted to pH 5.5, then let it drain until damp rather than dripping. Cut the drain slits in the cover once the slab is in position and only after it has fully saturated.
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" | 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 (this product) | 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 6" Hugo Block – Sits on this slab perfectly. The most common pairing we sell.
- Cultiwool 8" Big Daddy Block – The bigger block on top, for the largest plants.
- Octa-Mitter 360 Dripper on Stake – One dripper per slab is what makes per-plant steering work.
- Grodan Vital Rockwool Slab – The alternative, when you would rather run a whole row off one shared reservoir.
Frequently asked questions
Mini slab or a full length slab?
A mini slab gives each plant its own reservoir, so you can steer and harvest plant by plant. A full length Vital slab is cheaper per plant and simpler to plumb, but every plant on it shares the same water content and EC. Choose by how much individual control you want.
Which block goes on top?
A 6" Hugo or a 8" Big Daddy. Stand the block on the slab once roots are through the base of the block, and they will grow down into it within days.
Do I have to soak it first?
Yes. 24 hours in solution under 1.0 EC at pH 5.5, then drain. Cut the drain slits only after it is fully saturated and in position.
Can I re-use a slab?
Commercially they are treated as single-cycle. The old root mass and accumulated salts are what you are fighting if you try to run a second crop on one. If you want a medium you can flush and re-run, look at clay pebbles instead.
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