We grow them not simply because our cat likes some of them; they have this cooling appeal that pacifies any overheated (strongly coloured) perennial beds. The groundcover forms are more easy to use. The tall ones need some form of support.
Nepeta racemosa ‘Walkers Low’
It looks good when it is at its best; tends to be floppy as season progress. This is probably the most popular Nepeta in the market.
Nepeta transcaucasica ‘Blue Infinity’
I sowed these from seeds many years ago. The bluish flowers are pretty but it is floppy and need support.
Nepeta x faassenii
This plant originally came labelled as Nepeta mussini. My understanding is it is syn. for Nepeta x faassenii which is a cross between Nepeta racemosa and Nepeta Nepetella. This is relatively low, compact and flowers well.
Nepeta x faassenii ‘Blue Wonder’
This is low compact and flowers well. I think this is my best Nepeta in the garden.
This is my tallest Nepeta. Its flowers are showy, but it really need support, or it will look messy.