Rockwool is a very popular hydroponics growing
medium. Rockwool is a porous substance that forms
when a mixture of rocks, mostly basalt and dolomite,
is melted at high temperature and specially
processed. Given the material's neutral nature, it
is used to build plant-growing medium granules or
slabs, blocks, plugs, cubes, etc.
As rockwool is composed of 97% air, it is easy to
control the air/water ratio in it. Its porous
quality also enhances root growth.
Factors Supporting the Use of Rockwool
More than 95% of all greenhouse vegetable production
is carried out with the help of Rockwool -and for
good reason. Like mentioned before, rockwool allows
control over air and water supply, which are
essential factors for plant growth. It also provides
other feasible conditions to support a great crop,
leading to consistency in plant production and
yield, which is an important consideration in
Another pro is the easy availability of Rockwool
products in a variety of shapes and sizes. This
promotes the maximum utilization of Rockwool in
various types of hydroponic set-ups.
Since rockwool is present in various forms,
familiarize yourself with the different types of
products to be better able to select the appropriate
ones for your gardening needs.
Rockwool Granulates: This granulated form of
rockwool increases the absorbing capacity of the
growing medium and aeration for plants, thus
accelerating plant growth. You can use it as an
alternative to soil mix or mix it with repellent
Rockwool Starter Cubes: These cubes are great as
seeds and cuttings starters. Once the plants begin
to grow, you will need to transplant them into
appropriate mediums of your choice.
Rockwool Grow Blocks: Rockwool Grow Blocks are
full-sized growing mediums for transplanting
slightly bigger seedlings, with a couple of small
leaves and roots emerging from starter cubes. The
3'' and 4'' sizes are best bets if you plan to move
plants to rockwool slabs later on. For bigger
plants, go for the 4'' and 6'' block sizes.
Rockwool Growing Slabs: The special structure of
the growing slab allows uniform distribution of
water and nutrients. The slabs feature vertical
fibers that aid quick drainage. There are two sizes
to choose from. The 6'' slab is best suited for
growing plants like pepper and tomato while the 8''
slab can sustain crops like cucumbers, which have a
higher water need.