These plants like full sun, but they will not stand soil which dries out. Soil conditions vary in borders made along ditch sides or pond edge. Water does not travel far in heavy soil sideways, so the soil becomes drier the further you go from the source of water. Although needing regular moisture, some plants will not tolerate saturated soil, especially in winter when they will rot. These include Astilbes, Gunnera and Rheum. Others, like Myosotis, Acorus, and Houttuynia are amphibians, and will climb in or out of the water. This first list indicates plants which will thrive in water or water-logged soil.
GRASSES OR GRASSLIKE PLANTS FOR WATER EDGE
Ferns for water edge
PLANTS WITH ADEQUATE RAINFALL, DAMP, BUT NOT WATER-LOGGED SOIL
Ranunculus acris 'Flore Pleno'
GRASSES OR GRASSLIKE PLANTS TO COMBINE WITH ABOVE
Glyceria maxima (invasive plants)
Phalaris arundinacea var. picta 'Feesey'
FERNS TO COMBINE WITH ABOVE