Giving flowers to someone who would welcome and enjoy them certainly is a nice thing. But that may not be the case with a T. It may have an unintended effect-- like making him uncomfortable, worry about erotic transference, or force him to refuse them because they're against his boundaries. Giving gifts is always nice when you're thinking more about what the other person would want-- and less about yourself and what you want to give. Maybe flowers aren't the thing that would make T happy. Maybe a note of appreciation instead?