Nepeta 6 Hills Giant or Walkers Low?

[Delan3y]

I have Walkers Low which I love but want something to grow around my Gertrude Jekyll obelisk in a border. Would 6 Hills be better for this or is it too thuggish?

What about Nepeta Purrsian Blue? I have this and it is the most beautiful of the family in my mind and the size and shade of blue would look great with Gertrude.

I used to grow Six Hills Giant. It flopped and smothered nearby plants. I used to stake it and it was gorgeous early in the season but always out of hand later on.