This study determined the seasonal N uptake patterns of dogwood grown in a recirculating, hydroponic system. Intermediate rates of N at NH 4 - N to NO3 - N ratios of 1:5 or 1:1 produced the greatest plant growth while taking up less nitrogen. The majority of N applied at planting was not utilized and could be a source of environmental contamination. Peak N uptake was in late summer, although fertigation at this time could reduce plant winter hardiness. A second study evaluated the ability of a computerized injector to accurately deliver and adjust nutrient concentrations, and determined growth of containerized ninebark with recirculated nutrients compared with traditional non-recirculated fertilization methods. Nitrogen, P, and K concentrations dispensed by the computerized injector (recirculated and non-recirculated) were 35, 41, and 39%, respectively, lower than targeted values. Notwithstanding this result, recirculation reduced nutrient use by between 57 and 77%, and increased plant growth.