GROWTH AND ESTABLISHMENT OF PACIFIC NINEBARK (PHYSOCARPUS CAPITATUS) AND ATLANTIC NINEBARK (PHYSOCARPUS OPULIFOLIUS 'CENTER GLOW') IN RAIN GARDENS IN THE PACIFIC NORTHWEST©

Low impact development is an emerging concept for treating urban stormwater. Bioretention, an important tool to address this, utilizes the properties of plants, soil media, and microorganisms to infiltrate water and filter pollutants. Rain gardens, a form of bioretention, are shallow depressions in the landscape filled with soil media and plants. Plants are an essential rain-garden component. In order to expand the list of plants recommended for rain gardens in the Pacific Northwest, an Atlantic ninebark (Physocarpus opulifolius ‘Center Glow’) was planted in three rain-garden hydrologic zones: the wetter bottom, the dryer top, and the sloped transition zone. The Pacific ninebark (P. capitatus) was planted in the wet zone for comparison. Results after three growing seasons showed rain-garden zone did not affect growth or survival of Atlantic ninebark and there were no differences between the Pacific and Atlantic ninebarks. All plants grew well during the study.