acanthus spinosus

i have a acanthus spinosus which has become a problem. it has not flowered for two years and uses all its energy spreading new shoots in areas of the garden where i do not want them.how can i stop it from speading yet encourage flowering next year.

I think you're proably being too kind.  The best flowering specimens I have ever seen were at the base of a wall in almost no soil at the side of  a driveway.

Mine have never flowered as I have fertile soil and they do try to spread given half a chance.