Anise hyssop grows about 3½' tall in my garden.  It has very strong stems and doesn't require staking.  It is very easy to grow from seed, and will usually bloom its first year.  Flowers appear in July and continue until light frost if the flowers are deadheaded.  The leaves and flowers smell like licorice when rubbed between the fingers.  Butterflies like this plant, and goldfinches visit occasionally to eat the seeds.  Since agastaches aren't long-lived, it is best to allow some seedlings to grow.