How to deadhead nemesia, do I cut the whole stalk off?

I've got some nemesia plants, and I read online I should deadhead the flowers. But they keep producing more flowers at the top of the long stalk, and the stalk keeps growing. So should I wait until no more flowers are being produced at the top, and cut the whole long stalk off? Or do you even cut the stalk off while there are still one or two flowers at the top?
I'm thinking people don't painstakingly cut the tiny dead flowers off one by one ...
I uploaded a picture of one of the nemesia plants, and another picture of a an old self-seeded nemsia that has never been dead headed and has very long stems on it.
Many thanks.

 

I always cut them back when there are just a few flowers left at the top. Cut the stalk back right to the base and given them some water and a feed. I use Miracle Gro, but anything will do. They will re flower in around 2 weeks in my experience

 

Thanks so much AnniD, I think I'll do the same and I'll give them a feed too. I love how they keep flowering.