Abstract: A novel automatic tree waterer is provided herein. It is adapted to be connected to a stand which holds a tree, e.g. a Christmas tree, in an upright position. The waterer includes a hollow support base and a hollow two-piece body section. The lower body section is assembled to the support base by means of a slide coupled lip/coupling support lip to be airtight and watertight. The upper body section is assembled to the lower body section by means of male/female threads to be airtight and watertight. The upper body includes a male threaded upper neck. A hat including an inner well with interlock threads is assembled to the upper body by means of the male/female threads to be airtight and watertight. A water outlet is provided from the interior of the body section. A flow controller unit is connected to the water outlet to close the water outlet to enable filling the interior of the hollow two-piece section with water.