A water-retaining enclosure for surrounding trees and bushes and holding water, on flat or sloped hillsides. The enclosure is made of a resilient, polymeric material, such as wood/polymer composite. The bottom edge of the enclosure can have a sharpened edge or sawteeth for cutting into the soil. The upper edges can be tapered. The ends can be joined together to make a 360° ring using a watertight joint, or left open to form a 270° (¾) circle. The joint can utilize an elastomeric seal, finned connector, mating conical surfaces, interlocking flanges, or an interference fit to make it watertight.
