A system and related method for purifying indoor air comprising: a filter bed comprising a growing medium suitable for growing plants rooted therein and configured to be capable of sustaining an airflow therethrough between a top surface thereof and a bottom surface thereof； a micro-irrigation system comprising a plurality of irrigation source outlets for delivering water to the filter bed in a substantially-uniform fashion； an active region of the filter bed comprising that region of the filter bed configured so as to substantially have the airflow flowing therethrough； and micro-irrigation system configured such that water therefrom is capable of being projected so as to reach at least 50% of a top surface area of the active region.
