earth box

Anybody have experience using earth boxes outside for cannabis? I live in nor cal and I'm wondering about watering. Stays in the 90s all summer with low humidity. Any pros, cons, and tips would be appreciated!

So I just decided to order up some earth boxes.. I have always been intrigued to try them out . My main question is now , how many plants could I fit in one earthbox ? I know most people usually just go for a single plant , but could I get away with using say 2-3 plants in a single box & a...