I've read the same thing, Mark. I haven't seen any rigorous studies on
it, but that doesn't mean they're not out there. It rings true to me,
because my grandmother's generation occasionally would crush up and
dissolve an aspirin and water with the solution. The active
compound--acetysalicylic acid--occurs naturally in willow bark.

Since willows root easily in water at almost any diameter, you could
try getting a big fat willow cutting, suspending it in water, and then
using the water as a rooting solution. That way, you get a tree out of
it, too. I'd recommend the buttermilk for moss. The recipe I've always
heard was successful was to harvest some moss, knock off as much dirt
as possible, and put it and a cup of buttermilk in a blender. You can
use the resulting slurry to "paint" moss on wherever you need it.
Provided it has enough shade to keep from frying, you should have some
success. I've also heard you can use a can of beer instead of
buttermilk. If you try them, report back so we know the best way to do
this.

Mark Hill - President, EESiFlo Inc. wrote:
I've read that soaking willow shoots in a bucket of water results in a good
rooting medium.
Something in willow shoots that's a natural rooting hormone.
Does anyone know if it's possible to mash a bunch of new willow branches in
a big bucket to create your own rooting hormone ?

I ask this because I'm creating a new garden in my back yard here in
Pennsylvania with HUGE boulders as accents.
Unfortunately, the boulders don't have that aged look, and I was considering
covering them with a thin layer of dirt and trying to force moss to grow on
them. As usual, I'm looking for a shortcut.

PS ..... I have an unlimited source of willow trees on a creek bank.

Mark Hill - Harrisburg, PA - Zone 6