Terrarium definitely bugged.

I'm having a problem with the terrarium as well (on PS4).  I had collected 8 seeds before finishing the story and those have all grown fully.  I found and planted the Bleeding Gut and Milk Grass seeds after finishing the story and have played several hours on different planets since.  The Bleeding Gut has sprouted but not grown into an actual plant and the Milk Grass hasn't even sprouted.