Rockwool / Stonewool 4″ Gro Blocks Measures 4″ x 4″ x 4″ each Comes in a six pack.
Made in Denmark since 1969, rockwool (also called stonewool) is widely recognized as the ideal growing substrate. For any growing application, rockwool offers speed, ease of use and cleanliness. Grodan and Paragro rockwool is known for its top quality, consistency and performance. The raw material is basalt rocks and chalk. These are melted at 1600 C°. The lava is blown into a spinning chamber, which pulls the lava into fibers, much like ‘cotton candy’.
At full saturation, Grodan rockwool holds approx 80% of its volume in water, leaving 20% of tiny air pockets. It is wrapped in UV-degradable plastic and the stone wool can be re-used in your garden to improve the aeration and water holding capacity.