I can only find tiny bottles of dilute potassium permanganate hence, a follow up question, if you use potassium permanganate, where do you get it?

I would have thought someone with a chemical background would have answered by now...

I'm no expert, but I have used PP many many times to disinfect plants before putting them into my pond. First off, I got my 6 ounce bottle of PP from Sears a few years ago. It will be in the department that sells water filters. They sell it for regenerating iron removal filters.

Obligatory safety message: Be careful not to breathe PP Dust. Be careful not to splash PP crystals of mixture in eyes or on skin. Also PP will stain porous things purple.

Now, for plant disinfection, I put 1/4 teaspoon full of PP in 5 gallon Home Depot bucket. Then fill the bucket with water using the shower setting on the garden hose to agitate/mix the solution (CAREFULLY). Then I put the new plant(s) in another 5 gallon bucket and pour in enough of the PP solution to cover the plants. Usually have to push and hold the plants down somehow to keep them submerged. I keep them submerged for 6 hours, then rinse with water and put them into the pond.

It has worked for me - Don't remember who gave me the mixture info now, but I've done many times - Your mileage may vary.