Hardy purple asters are susceptible to root rot during long, cold winters so grow them in a rock garden, raised bed or sandy, loose soil. They are also easy prey for a virus that causes \"aster yellows disease\" so if you consistently see your plants turn yellow and die you may want to try a different fall bloomer such as sedum 'Autumn Joy', winter pansies or Japanese anemone. Do not give these native plants rich soil or a lot of water - they are native wild flowers and do best in fields and average soil. Keep growing, Marianne Binetti