What is the best way to plant it ? And how often to water it?

It’s easy to grow provided your climate is mild enough and will take frosts down to around -6C. Will grow to around 1.5m high x 1.8m wide (5 x 6ft). It strikes readily from cuttings and you may be able to use that piece as a cutting. Remove the flower buds first.

That is one of the many cultivars of Hebe speciosa, now more correctly known as Veronica speciosa. It’s native to New Zealand, which is where I’m based, consequently you can see many more hebes on my website at http://www.botanicalstockphotos.com/photos-shrubby-veronica-1432.htm . The hebes were originally classified in the 19th century in the genus Veronica, then they were split off into other genera, such as Hebe, Parahebe and Derwentia, but the latest research has put them back in Veronica, though this may take a while to be fully accepted.