W wrote:
songbird wrote:
W wrote:

What is the most economical source for a large bag of small red lava
rock,
to be used as a replacement for pumice in a succulent soil mixture? I
also
want to use the red lava rock as a mulch.

the stuff floats away easily, so not the
best mulch if you get heavy rains, winds or
floods.

Are you confusing lava rock with perlite? Perlite definitely floats.
Volcanic aggregates (i.e., either white pumice or red lava rock) sink in
water.

nope, no confusion at all. perlite is air
expanded silicon. pumice can float and the
color varies just as the lava rocks can vary,
but the point in common to all of these as
marketed is that they do tend to have air holes
throughout.


I did a quick test with 10 smallish red lava rocks in a bucket of water, and
they all 10 sank.

they might sink, but they are lighter than
a normal rock and they move much easier by
water and wind.

i've used some as mulch here and they wander
around. you need a pretty good border to keep
them in place.


songbird