Grodan Gro-Slab 36x12x3 in | Bag of 8, Improved Stone Wool

What the Grodan Gro-Slab 36x12x3 Gives a Row

Each slab measures 36 x 12 x 3 in. The 30/75 code Grodan prints on this family is the metric cross-section, 30 cm wide by 7.5 cm deep. A bag holds eight slabs, and a pallet takes eight bundles. Width is the whole reason this body exists. A 12 in face carries a row of plants across one continuous root volume instead of one plant per narrow strip. Roots from neighbouring plants then share the same water and the same EC, which evens out the whole row. Grodan builds the Improved wool with an advanced wetting agent. That agent is what gives even water content and even EC both through a single slab and between slabs in the same run. Resaturation capacity is high, so a slab allowed to dry back takes water again without channelling. The fibre is inert and hydrophilic, which means it holds nothing of its own and lets your solution set the root zone. Slabs arrive inside a labelled, biodegradable, UV-resistant sleeve that keeps light off the wool so algae cannot start. Grodan lists this one as item 320566.

Running a 12 Inch Rockwool Slab Across the Bench

A 12 inch rockwool slab is a bench-scale decision rather than a pot-scale one. Laid end to end down a gutter, the row becomes a single hydraulic unit. That helps when irrigation is uniform and hurts when it is not. One weak emitter shows up as a dry patch shared by several plants at once. Check emitter output slab by slab before the first transplant rather than after it. Saturate the wool fully before anything goes into it. Fill until the sleeve goes taut at the seams and give it half an hour at minimum. Cut the drain slit at the lowest point beneath the seam so the slab finds its own level. Cut plant holes to the block size rather than larger, because a loose block leaves an air gap the roots have to bridge. One or two drip stakes per hole is usual, and a stake never goes through the base. Keep the blade off the wool when opening the foil, since a nicked fibre face weeps for the rest of the run. Dry-back is the steering lever on a slab this wide, and it moves more slowly here than on a narrow body. The greater volume buffers a mistake and also delays a correction, so changes want making in smaller steps.

Key Features

• 36 x 12 x 3 in slab: The widest body in the Improved Gro-Slab range.
• Bag of eight: Eight slabs to a bundle and eight bundles to a pallet.
• Advanced wetting agent: Even water content and EC within a slab and between slabs.
• High resaturation: Takes water again after a dry-back without channelling.
• Inert hydrophilic fibre: Holds nothing of its own, so your solution sets the root zone.
• Single or multi-plant: The width carries a row rather than one plant per strip.
• UV-resistant sleeve: Labelled and biodegradable, and it keeps light off the wool.

Technical Specifications