Phisherman wrote:

"Ed" wrote:

What is the difference between Vermiculite and Perlite?


In use, vermiculte holds moisture. Perlite speeds drainage, gritty,
lightweight. Vermiculte is very good in getting woody cuttings to
root (never tried rooting with perlite but I guess it might work).
Both mediums are inorganic and sterile. For some reason it is harder
to find vermiculite for sale, perlite is availailable in many stores.

Vermiculite is a hydrated basaltic mineral which expand when exposed to
hight heat. It resembles mica pellets. It can be made from mafic lava
such as that in Hawaii. It is primarily SiO2 with magnesium and iron
oxides.

Perlite is an amorphous volcanic glass with a high water content. It
can be made from obsidian (black glass-like lava). It looks like white
styrofoam BBs. It is also a byproduct of steel manufacturing but this
is too high in boron for horticultural uses and is only used for
aggregate, etc., not horticulture. Do not use pearlite, it is a
different material. Perlite is typically 75% SiO2, 15% Al2O3, and
smaller amounts of sodium, potassium, iron, magnesium and calcium
oxides. 14% all perlite is used for horticulture. Perlite tends to
last longer and has a more neutral pH

The are both sterile materials so they are frequently used in plant
propagation where any water molds cause severe losses. They are usually
used in combination to provide the optimum balance between drainage and
retention of water.
--
Pardon my spam deterrent; send email to
Visit my Rhododendron and Azalea web pages at:
http://rhodyman.net/rahome.html
Also visit the Rhododendron and Azalea Bookstore at:
http://rhodyman.net/rabooks.html
Cheers, Steve Henning in Reading, PA USA Zone 6