I'm really considering dropping the talent. From what I've read the trigger rate is very low and it only works off traps, prisms, dispels, and charms. I've read that having a trap placed on you might trigger it as well? There also seems to be confusion as to whether attack spells activate it. I have not noticed attack spells or healing spells to activate Green Thumb.
As a life there isn't any great charm spells. There's weakness but that's hardly worth using. If you are support/healing as life the only spells this would likely activate off are traps like feint or maybe a dispel. I really don't see the value of this talent with how hard it is to actually trigger. If I wanted sanctuary so bad I don't see why I wouldn't just spend the pips to get the 50% version instead of hoping for a unlikely trigger on spells that aren't that useful.
I'd like to know if any other players with life wizards have used a pet with this talent and how it has worked out for them. It seems like a huge waste of time. It think an aura proccing talent would be more useful since they trigger off of wards, blades, bubble (like sanctuary lol), and passing.