Yep, those are the spacers between blades. I used the disk axle to stack them on.
The original base was a cast front wheel off a Farmall F12. When I built the new planter and went to move the hanger into it, the welds let go (cast iron wheel and cast iron spacers...well beyond my welding capabilities) so I drove a suitably-sized piece of pipe into the ground, tamped stone dust around it to firm it up and then set the hanger into it.
It's a sort of hobby of mine to build "sculptures" out of junk farm equipment. Some examples
here for anyone interested.