Grodan Mini-Cubes


SKU: grodan Category:

Grodan is a long time manufacturer of inorganic rock wool horticultural media.  This product is manufactured by melting basalt and spinning it into fibers, much as insulating fiberglass is made.  The fibers are produced as a mat, then cut into smaller pieces for use.  In this case, they approximately 1 cm cubes.  The fiber is approximately 50/50 hydrophilic/hydrophobic, so is supposed to remain fairly airy.

I did a little experimenting before use:

  • I filled a 3.5″ square flower pot with the dry cubes – they weighed only 44g.
  • They were soaked in RO water for 36 hours
    • Saturated, they weighed 272g.  After 5 days of sitting open in warm, humid air, only 20% of the water had evaporated.
    • The saturated cubes occupied approximately 55% of the container volume, leaving 45% air space.
    • The pH of the soak water was 5.4, so should be fine right out of the box.
    • The EC was only 20 µS (for reference, a 100 ppm N solution of K-Lite has an EC of 710 µS).

The material can be used alone or mixed with other, inorganic media like perlite or LECA.

Prices includes shipping to US addresses.

Additional information


1 gallon, 3 gallons