Hakone grass and ornamental sedges are both plants that tolerate moist soils and shade. They are rated hardy to zone 4 and some sedges survive in zone 3. Start with a few plants and see how they fare in your garden. The 2009 perennials plant of the year, Hakonechloa macra 'Aureola' (Hakone grass) has chartreuse leaves with a narrow green stripes. Another variety of this grass, 'Albo Striata', has a wider leaf with a white strip. These look great with large leaved blue hostas. Hakone grass can take a few years to get established so be patient. Carex elata 'Aurea' (Bowles Golden) is probably the most reliably hardy of the colorful sedges. It has narrow yellow-green leaves. Carex morrowii 'Variegata' (Silver variegated Japanese sedge) has green leaves with narrow white leaf margins. These also combine well with hostas.