Mayne Tall Planters with a removable Tray, Patio Planters and Window Boxes all have a "Sub-irrigation" reservoir system. Capillary action allows water in the reservoir to soak upward keeping the soil and plant roots moist creating a self-watering effect.
Regular watering is required for the first few weeks giving the root system time to develop. Once the roots have grown down into the troughs of the planters, the plants will be able to pull moisture from the reservoir. With this system you will find the potting mix stays moist longer than traditional planters. To avoid over-saturation an overflow hole allows excess water to drain out.
Although "self-watering" containers still need to be watered they need to be watered less frequently than your typical planter.