Remove flower heads as they fade.
The clump will grow over a few years and then can be lifted and divided to improve flowering. Do this after the plant has flowered. Lift the rhizomes with adhering compost and discard any old rhizomes from the centre of the clump. Divide carefully, preserving as much of the root system as possible, and replant in a new area. Dress the soil with blood fish and bone to help build the rhizomes for next years flowers.
This plant likes an open sunny position in well drained soil. Plant with the rhizomes level with the surface of ground, as sun on the rhizome matures it and it will flower well the next year. Water well after planting, and in dry or windy conditions
Ensure that temperatures are mild and all chance of frost has passed before planting out, as Braithwaite is a hardy plant.