Russelia presents an attractive display in the sub-tropical climate of southern Queensland, Australia. However, I could not recommend it without a warning. I planted eight potted specimens of the red and yellow blooms in a six-square-yard oblong patch alongside a driveway in the spring of 2011 in unfertilised soil. Then followed nearly four months of continuous rain (Australians will long remember this period of Queensland floods). Eight months after planting the original eight had turned into nearly 100 deep-rooted plants jammed into the same space in hardened soil. I have dug these out by hand and mattock one by one - very hard work indeed. I can only recommend that gardeners give careful thought before planting these viciously aggressive and invasive monsters, even if they look attractive in a pot.
Huh, you've just IDd a plant growing in a bed at the base of a friend's house. Hardened soil, like yours, but no trace of invasiveness. In fact, it's been a godsend during the drought years, staying lush and flowering with virtually no watering. (She has the yellow, red and pink varieties.) It's been growing in this bed for years, possibly decades but certainly before the drought, without problems. Just providing proving yet again that what's a good hardy plant in one situation can be an aggressive monster weed in another!
Commiserations on the mattock digging--back-breaking work at the best of times. And thanks for (unwittingly) identifying the plant for me :-)