Suppressing -> Taming -> Controlling
They're all closely connected to each other; it depends on how you interpret controlling. I don't think that Mokuton allowed him to control them the way Madara controlled Kyuubi, namely obtaining full control of their spirits and fully controlling their actions. I guess he was 'merely' able to suppress their power in a very efficient way. Not just that his Chakra was able to suppress theirs (see Yamato doing so by using Hashirama's technique and a cristal with some of his Chakra), the small trees of Yamato's weaker Mokuton version were able to restrain the imense power of Naruto's Kyuubi no Koromo with four tails for a while.
But I might be wrong, it's something that cannot be proven yet.