A water retention device is used in conjunction with a plant container. The water retention device comprises a resilient plate structure forming a central cover, a sidewall extending from a perimeter of the central cover, and a slot extending through the sidewall and a portion of the central cover. The sidewall engages an inner surface of the plant container and supports the central cover at a spaced distance above a growth medium. The resilient plate structure is manually configurable to open the slot for receiving a plant stem so that the plant stem extends through the central cover. Water may be supplied to the plant container using either a spray stake disposed under the central cover or using a trough formed in the central cover. Where a spray stake is used, the inner surfaces of the sidewall and central cover may include ribs that deflect water.
