For those who don't want to worry about frequently watering large planter boxes, this black rectangular water reservoir does the trick. Made from heavy duty plastics, you can order self-watering planter reservoirs online with or without a PVC fill tube.
Turns any planter box into a self-watering planter
Easy assembly in seconds
Holds approximately 3 gallons of water
Comes with PVC Fill Tube
Watering coverage reaching 9" past reservoir edges
Minimizes maintenance cost and plant replacement