I don`t. I have one pot that grew all winter and flowered last month. In my big
garden I always just pulled out or cut the tough-stemmed flowering bits so they would not seed all over. The flowers are edible by the way.
But the plants continued throughout the season.
Also in my big garden, I cut them down in December but here where it`s warmer, I just let them look after themselves. Seems to work.
They also need to be divided every few years or they become a bit unmanageable.