Posted: 03/09/2012 at 16:02
Hemerocallis associate well with hostas and like life near water. They're not expensive and soon bulk up so can be divided to create more plants. Astilbes also like moist soil. I have a purple/lilac flowered one which is spreading very happily ina damp bed and have recently planted some white forms near our own unlined pond.
Forms of gunnera (not all as huge as mannicata) like damp soil as do eupatorium, lysimachia Firecracker and Vesuvius, hydrangeas, miscanthus zebrinus, assorted irises (check for marginal pond varieties), iris sibirica, forms of salix with colourful stems that you cut back in spring to keep the stem colour, rodgersias, acteas, aruncus, dicentras and so on.