Friday Fabulous Flower - a yellow loosestrife

A sort of rock garden area between a path and the margin of our lily pond was screaming for some color.  Without a whole lot of thought, or knowledge, TPP grabbed some of these prostrate yellow loosestrife plants from a local garden shop and stuck them into the ground.  Wow, do they look great or what!  Low mounds of yellow-green varigated foliage and very cheerful aggregations of bright yellow flowers with red centers at the tops of low aerial stems (Lysimachia congestifolia).  What a great looking plant for a rock garden, and perfect for this location.  As a bonus, bunnies don't seem to eat it.  However, it's not even slightly hardy so it'll have to be treated as an annual.  That just isn't right, but what are you going to do?  A bigger species used to grow nearby, but it was rather an aggressive spreader and did not play well with others.  Will this turn into an annual concession to annuals?  Maybe some cuttings can be rooted in our glasshouse and over-wintered that way?