I have read about growing radishes or potatoes in a bed of 6"-8" of perlite using drip. I grew some radishes in peat/perlite mix and a rock wool starter cube last year as a trial. They grew well and really fast, but I messed up the nutrients and picked too late and the most the radishes were huge and pithy and not very tasty. The radish grew right on top of the rock wool, which was not planted deep enough. Next time I would not use any rock wool or starter cube, just directly seed into medium. Definitely worth another try this year. I think for potatoes, go to farmers market and buy some grown locally, then let grow eyes(roots) and transplant. Good luck!

I need some input about growing Potaoes hydroponically, I tried before growing successfully Radish and Turnips hydroponically in pure Perlite. If there is a link for hydroponic potaoes I appreciate much your help.