This rather uninteresting wheel was produced by A.H. Hoffman, Inc., makers of plant-growing assistance products. They charged their customers ten cents for the privilege of choosing either their sterilized cow manure or cocoa shell mulch ("has pleasant chocolate aroma"). Just turn the pointer to the plant you've got and it tells you which product to use.
Or does it? Very often, you can't quite make out which of the products the tiny arrows are pointing to. Nice job, A.H!