I tried this not too long ago in an AV on my 70 druids. Even in crappy gear, the wildgrowth spam keeps my 5 tree's, or anyone around me up forever. Also to topic, I would not say the revitalize effect stacks, but it procs independently without hidden cooldowns ( hope I worded that correctly). They were the ultimate turtle saver, even the cause of them. Note that ALL 5 were tree's, I have yet to find the optimal amount of tree's for this to be effective.

1. I never ran out of mana, NOT ONCE
2. That much healing can only be beat by focus fire, or mass cc
3. Crazy stupid one button spamming fun!
4. Worth trying at least once if u have a druid team.

PS. This was before the patch 3.2, not sure if anything changed.