The basic purpose of the fill port hole is to give direct access to the reservoir in order to fill it faster.
Mayne Planters are molded with a double wall design that creates an internal water reservoir. To provide direct access to the reservoir we recommend drilling a 3/4 inch hole in the top or back side of the planter. To cover the hole we have included a rubber plug that can be easily removed to fill or drain the planter as needed. The reservoir will still fill without the hole by excess water filtering through the soil.
Please note the rubber plug is provided as an added feature so drilling the drainage hole is completely optional.