OH! I have one of these. I didn't know about being able to use the leaves as pesticide. That's really interesting! Now I HAVE to get it into better shape so I could harvest some of the leaves.
It's been badly neglected.
Too many weeds around it, including Ostrich Fern that's taking over that area. It's unfortunate that Azalea Lace Bug doesn't seem to be affected by its toxicity
This year, I've turned my attention to this area and am working on creating a mixed shrub border (Rhododendron, Astilbe, Japanese Andromeda, Arunculus, Arrowwood Viburnum, Carolina Allspice, Ostrich Fern, more Astilbe, and Black Cohosh), with a "weeping?" Blue Spruce on one end.
Oops, just realized this is the Japanese Gardening Forum. I'm afraid my shrub bed is going to be much less orderly or refined....