Grodan also makes Pargro Rockwool, a lower cost alternative with nearly identical quality.

Rockwool is made from molten rock spun into fibers like cotton candy. It's then pressed into different shapes and cut into cubes and slabs. The cubes and slabs feel like a sponge and will not breakdown. The small Multiblocks and Miniblocks can be used for starting cuttings or seeds. After the plants grow out of the small blocks, you can place them in the holes in the larger growing locks. From there you can place them on a slab for larger plants. Although the rockwool can be heat sterilized after use and re bagged, most hobby growers just throw them away after use. The Grodan Growcubes are small squares of rockwool about the size of a sugar cube. They are used for filling pots or mixing with Hydroton for added moisture. The Granulated rockwool is also for filling pots and is less expensive than the Growcubes but does not have the same aeration.

Growing Blocks are used for small plants in a flood / drain tray

Multiblocks are used for seedlings and cuttings

Miniblocks for seedlings and cuttings

Granulated for filling pots

Hugo Blocks for larger plants, best with a drip system

Slabs for large plants watered by drip irrigation.

Growcubes in a pot

Learn More About Rockwool.