I was thoroughly underwhelmed by Home Depot's 90 minute gardening "class".
I learned one handy mnemonic for building a container box garden: you want your thriller, your fillers, and your spillers (thriller is the center plant, fillers around it, then the spillers are the ones that will spill out the sides of the container box).
It basically wasn't a class though. More so "we'll all chat while the staff does all the planting".
Come on man. I wanted some dirt under these fingernails!