You can't get Natural as a result from a bean anyway. There's an "All Natural" potion that should work on everything (not sure about RSTU... don't quote me on that one), just be very careful you have the right pet selected before you use it.
You can use a DK on any pet that has the color no matter what color they are, so if you just want an orchid one instead of natural then go straight to the orchid DK. It overwrites whatever color it was before, whether natural, dyed, or hatch colored.