The backyard is younger and will mature over the next couple of years. I'll be scattering seeds whenever they're ready.
Judy, Dame's Rocket has not proven invasive at all for me. It has a taproot and we have heavy clay soil. I did deadhead last year before the majority of the seeds were ripe. I left a few but haven't noticed any new seedlings this year. The white is still the more fragrant of the two. I want some in the backyard next year, so I will leave it to set seed this time around.