I bought a very small Hoya lithophytica cutting in the spring of 2013 not knowing anything about the plant other than I had never heard of it.  It pretty much sat there for months without growing.  Finally in a warm grow tent it started to slowly grow during the winter.  Instead of growing up like most Hoyas, its stiff little vine grew straight down.  I had to keep raising the pot so that it would not grow into the screen that cover the trays of water in my tents.

Finally I gave up and put it into a hanging pot as it only wanted to grow straight down.  Shortly there after, I must have over watered it as it quit growing.