Abstract: Collars, for supporting plants by the base of their stems with the major portion of the root structure extending downward into an aqueous hydroponic medium, have upstanding sidewalls and bottom end structures that support the plant while leaving at least about 75 percent of the bottom area open for the roots to extend through. The collars are very small having a volume less than about one tenth that which would normally be considered adequate to conventionally culture plants in a solid support medium. Vertical foils extend radially inward from the sidewall to prevent the roots, in their early stages of development, from spiraling around the sidewall.

Abstract: Plants are hydroponically grown on rafts that float on an aqueous nutrient medium. The rafts have arrays of openings that extend from their upper surface to their lower surface for receiving plant-containing collars that dip into the aqueous medium.To provide efficient plant thinning without plant destruction, a fraction of the openings of the array of each raft is filled directly with plant-containing collars and the remaining plant collars are placed in a grid that overlies the raft and has openings aligned with a fraction of the openings of the array.