Divide it into fist-sized sections, discarding any old woody parts. Dig over the soil, add compost and a general fertiliser and return one of the divisions to the original planting position. With taller varieties it may be necessary to provide support with canes or wire supports. Snip off the dead heads of flowers at regular intervals to promote re-growth. When deadheading plants with long stems, cut each stem back to the next growth point or set of leaves.
Most perennials die back in winter, but some retain many of their leaves.
Remove dead leaves before new growth starts in the spring.