Sub-irrigated planter (SIP) is a generic name for a planting box used in container gardening and commercial landscaping. A SIP is any method of watering plants where the water is introduced from the bottom, allowing the water to soak upwards to the plant through capillary action. SIP's are available as products, under brand names such as EarthBox, Grow Box, Earthainer, or as do-it-yourself projects made from plastic buckets and boxes.
The patented EarthBox was developed by commercial farmers. The EarthBox measures 30 by 13-1/2 by 12 inches (l x w x h) for a soil capacity of 2-1/2 cubic feet. The box rests on four wheels and easily rolls into full sun and then moves to the back row so another Earthbox can get sun rays. The growing kit includes fertilizer, dolomite, and two germination covers. EarthBox is expensive at $44 to $55 (with shipping).
Blake Whisenant, Inventor of the Earthbox, demonstrates how it works:
Read more here: EarthBox - sub-irrigated planter, garden container for vegetables