Rockwool Slabs
Rockwool slabs for dripper systems and greenhouse growing: a sterile, consistent medium that holds water and air in the right balance and takes a transplanting cube straight in.
About Rockwool Slabs
How rockwool works
Spun mineral wool holds a lot of water without going airless, so plants on a slab can be fed by dripper several times a day. Nothing in it feeds or buffers the plant, which gives you full control and makes it the commercial greenhouse standard for tomatoes, cucumbers and peppers. Slabs stay wrapped in their plastic sleeve; cut holes in the top for the cubes and slits in the base to drain.
Preparing a slab
Soak it for a day in water adjusted to about pH 5.5 before planting, because dry rockwool is alkaline. Sit propagation cubes into 75mm transplanting cubes, then those onto the slab once roots show. The cubes are under Plugs & Substrates in Propagation. Keep run-off draining and don't let a slab dry out: rockwool is hard to re-wet.
