Many perennial weeds grow from underground roots or tubers making the path to weed-free perennial gardening much tougher. Inputs to the seed bank are shown with black arrows and losses with white arrows. Your plant will do better in a growing medium which is damp but not soaking wet.  Source: <a href=http://www.pierpark.com.br/?p=25127>http://www.pierpark.com.br/?p=25127</a>