A vegetation culture active agent delivery medium is provided that includes dense mineral granules, comparatively less dense cellulosic granules, and an active agent in simultaneous contact with the mineral granules and the cellulosic granules, the active agent present from 1.times.10.sup.-5 to 10 total weight percent of the medium. A formulation of an active agent is applied to one type of granule as a mixture thereof. Through control of the relative amounts of mineral and cellulosic granules, a controlled medium density is readily adjusted between 35 and 60 pounds per cubic foot.