Activity

What is the grade and the largest amount of water you are dealing with? The planter needs to be designed to handle whatever nature throws at you.  You can retrofit the drain like Chris said to become the overflow at the down end of your planter. If you have a lot of slope, check dams can hold the water and pool it to infiltrate fully. Then the rest will go to the overflow. Will this be a bump out or a taller planter?