dun1kirk.. ?? what do u want to use the vermiculite/perlite for??
or just interested in difference??
i'll throw my 2cents in..:)
im off perlite now.. and dont use vermiculite..except
when its in a prepared seed starting mix..
perlite ..for my uses (potted plants) isnt coarse enough..
and it does break down..not good for drainage..
so... i use pumice.. for my use i get the largest i can..
just around 3/8"
and pumice ..unless crushed.. lasts..
Vermiculite holds a LOT of water, whereas Perlite holds almost no water.
Vermiculite crushes easily, so it doesn't improve drainage for long unless the soil is absolutely undisturbed.
Perlite never crushes, so the drainage improvment last forever.
I like shredded bark (for example bark mulch, but finer). It holds a little bit of water if it's gravel or grit-sized, and that size really improves drainage in containers, trays, raised beds or plain old soil.
Bark holds a decent aount of water if it is like powder or fine fibers. But it doesn't form a soggy, dense mass like peat, as long as the bark has some gravel or grit-sized grains (1/16th inch to 1/4", or 1-5 mm).
Coarse bark nuggets make great top-dress mulch because water runs off the chunks. Fine stuff softens clay or holds water in sand.
It breaks down much slower than wood, and cuases much less nitrogen deficeit. When it breaks down, it contributes humus to the soil, like peat.
And it is one of the cheapest soil amnedments: $4 for 2 cubic feet.
You can screen it with 1/2", 1/4" and 1/8" hardware cloth, or just rake out the big chunks.
i totally agree with rick !!!
i must be on my 20th bag (2-3cf ea) of pine bark
as major component of my potting mix..
for super discussion on good potting mix..check out
tapla,and others on containers forum..
good luck to ya...