A container for plants is defined by a bottom and side walls, and a drainage riser extending interiorly from the bottom, the riser having drainage openings adjacent the interior extremity and including an opening communicating through the bottom. A removable plug is provided for closing the bottom opening,...http://www.google.sh/patents/US5042197?utm_source=gb-gplus-sharePatent US5042197 - Plant container having selectable drainage characteristics
