PERENNIALS FOR DIFFERENT PURPOSES : Page 662
Hardy Sun-flower Cone-flower
b. To be divided every three years:
Armeria (in variety) Phlox paniculata
Sea Thrift Garden Phlox
Iris (all varieties) Thymus serpyllum lanuginosus
Iris Downy ThymeViola (in variety)Violet
c. To be divided each year:
Anthemis tinctoria kelwayi Bocconia cordata
Hardy Marguerite Plume Poppy
Aster novae-angliae (in variety) Chrysanthemum indicum