I e-mailed craig at the same time I posted and he was kind enough to respond. I don't think he will mind if I share. Andy
Hey Andy,
Looks like you got yourself an Amorphophallus paeonfolius there....pretty stinky when it blooms, which won't be this year as you get a leaf or a bloom and you got leaf.
Feed it up and it should bloom next year,the tuber needs to be about softball size. Come fall sometime it is going to go dormant on you...they all do, well except A. titianum and A. gigas.
As for the fertilizer.....look for something like a Peter's 20-20-20 foliar feed. The dilution rate is usually 1tsp/gal. Cut it back to 0.5tsp/gal and you can use it weekly. The regimen is often referred to as "weakly, weekly". Primary thing to remember is they are heavy feeders and they do not want to dry out....until they go to tuber and they need to be stored dry.
Hope that helps.
Craig