Posted: 14/08/2015 at 12:26
I think the problem is it's in a pot.
I grow Fascination, Alba, Erika, and they like good regular moisture and good root run. I posted a picture 3 weeks or so back and it grows 5' plus. As far as Im aware veronicastrums ( fantastic structural and flowering plants) are robust, healthy and problem free.
although it does enjoy good moisture the humidity, etc. and being in that small pot probably caused your issues.
get it into the ground,,in good well fed, moisture retentive soil