CAUTION: Dry perlite produces an
obnoxious dust. Wet it
down before using it.SAND - both construction or
horticultural - was much more popular as a
soil ingredient before vermiculite and perlite
were available. It performs many of the
same duties in the planting mix; stabilizing
water retention and loosening the structure.
The problem with sand is its weight. Even a
cupful of sand adds considerable weight to
a container.
GRAVEL - holds a little water on its
surface and loosens soil. It is heavy and
tends to sink in the medium. It is sometimes
used alone in hydroponic mixes.
LAVA - holds water on its irregular
surface and holes in its structure. It is
lighter weight than gravel. It is sometimes
used as a hydroponic medium. Clay pellets
are sometimes used in place of lava
because they are lighter weight Pea size
pieces are the best to use.
STYROFOAM - is hydrophobic, and is
used to keep mediums dryer. It is extremely
lightweight and tends to float to the surface
of the medium. Usually the little balls are
used but sometimes irregular chips are.
PEAT MOSS - is chopped and decayed
moss. It performs many tasks in planting
mixes. It helps to retain water and holds
nutrients and is a nutrient buffer which