It is a herb from which you can use both leaves and flowers. I found it to be fairly drought resistant and completely cold resistant. It can be trimmed back in spring but I have sometimes lost plants if trimmed too much. The pure blue is very nice but recently I found I can only get 'mixed' colours which can be a bit washed out with pale pink, white. Worth trying to grow it from seed to be sure of the colour. Should be grown more often IMHO.
Happy Hyssop, Yvonne