I have 3 kerria japonica bushes, which bloomed beautifully this spring. One is the lower, spreading kind with small, single flowers, and the other two are the much taller ones with larger, double flowers.

I've read that they will bloom all summer, but I'm not sure how to achieve this. Do I just deadhead the whole bush (a long and tedious process), do I cut them back almost to the ground? Something else?

Suggestions much appreciated.