I could not seem to manage a Sakura either but then I took a failed attempt Flower and Tree and fed them to level 7 and got one in the EBI the first time. When trying for my second I did the same but fed both to level 4 and put them in the EBI and now I have 2! Doesn't hurt to give it a try5 days trying to get sakura and still no luck just a load of trees lavas and poison
But I'm keeping them so I get a silver plant shrine
A lot of trees