ROCKWOOL - is the most popular
substrate. Originally it was used as an
insulating material in home construction.
Then commercial greenhouse growers in
Europe started to use it for their crops.
Rockwool looks a lot like fiberglass. It is
made by heating rock and extruding it into
thin threads. Rockwool comes in pre-
pressed blocks and filled bags. It is
lightweight and it holds a tremendous
amount of water, more than soil, but allows
plenty of air in. It comes in several forms,
blocks and cubes of various sizes, bags
filled with loose fiber and bales of fiber to
be placed in containers. It is reuseable for
several crops.
CAUTION: Rockwool releases
noxious fibers when it is
dry. Before growers use
rockwool, the material
should be wetted. A face
mask and rubber or
leather gloves, should be
used. Body should be
covered with a face mask
in place.