Speaking only from my own experience and just a couple of others - don't do anything upside down. It simply defies nature! None of us had any luck nor will we be doing it ever again!
If you're lacking for space or just want to try everything cuz it's all so new and fun - go for it!! YUP, TRY IT ALL, what the heck, huh?!?!
Yep, I agree. I grew petunias upside down and rightside up. Rightside up grew many many pretty flowers per plant- I don't know how many total but at least 5-10 at a time. Upside down got me two or three flowers the entire year.