I planted day lilies 5 years ago. They seem to be growing very well, however, the last two years they have not gotten as many flowers. The lilies appear to be healthy and are slowly spreading. I have not fertilized them since they were planted. Should I be and if so, when and how much? Do I need to be doing anything else with them after years of growth? They are growing in various location in my mulch beds.
Thank you for the help.