clausa is highly rhizomatous and can become invasive in the right conditions. Grow it where nothing else likes to grow!
Consider the lilies of the field, how they grow; they toil not, neither do they spin: And yet I say unto you, That even Solomon in all his glory was not arrayed like one of these. Mat.6:28-29
I just found a hosta that spreads so fast it might be considered 'invasive' !