The simplest form of container gardening is a flower pot. The gardener is tasked with maintaining optimal levels of light, moisture, nutrients, and drainage for best results. "Self-watering" plastic pots with reservoirs and wicking plates are obtainable at most garden centers and big box stores. More advanced container systems employ reservoirs and plant feeding mechanisms to achieve a less labor-intensive solution.
A more ambitious container solution is available in the form of the well-regarded Earthbox©. At 30"L by 15"W by 12"H, the Earthbox is capable of accommodating several plants in a relatively compact form factor. The oblong container features a perforated platform raised 2" above the bottom by a plastic gridwork. Each rear corner of the platform has openings to allow soil to form wicks into the reservoir. A watering tube allows easy refill of the reservoir, and a reversible black/white plastic cover provides moisture retention, heat retention/reflection, and weed control. A drain hole in the box positioned just below the platform prevents over-watering.
The Earthbox uses a mechanism known as a gradient system to allow the plants to draw moisture from below as needed, and for nutrients placed on the surface of the soil to be drawn into the soil in an almost osmosis-like manner.
In the time since the photos were taken, the Earthbox has been redesigned. The shape is more aesthetically pleasing, a variety of colors are available, and the overflow has been moved to the bottom. Previously optional casters are now standard. A starter pack of 7-7-7 fertilizer and dolomite (for calcium) are now included.
To make your own self-watering self-feeding container units see 5-gallon Bucket Tomato Containers.