Experts and BHG readers answer.
What can thrive in large oversized planter boxes that can offer up to 6-8 feet of privacy
Thanks for writing. Those boxes sound a little small for bamboo, but you may be able to get away with varieties such as Fargesia Green Screen or Fargesia Green Panda.
Otherwise, you might look at shrubs such as ceanothus, quail bush, coyote bush, coffeeberry, or toyon.
---Justin, Senior Garden Editor, BHG.com