We've trialed quite a few veronicas, most of which didn't (I'm using past tense for a reason) like our summer heat, but one that scored at the top of our list was Veronica 'Eveline'. I just snapped this photo of it in its prime right now at PDN. http://www.plantdelights.com/Veronica/products/382/
Before I forgot, I hope everyone is having a great Memorial Day weekend, whether you're traveling or playing in your garden... Enjoy!