here's a close up of some of the spent flowers

thanks again

IME you definitely want to deadhead it. In my garden it seeded so prolifically that I removed it in its second year and still pulled seedlings for 5 years. I love the scent and the umbels of flowers are great at the back of the border, but I am not fond of self-seeders since my deadheading isn't as prompt as it should be at times.

How far back did you cut it?

Thanks again!

Cut the long stems to the base. They're done.