I would recommend getting clones of known potent strains of Phalaris, and cutting the grass before seed is produced.

I chose clones of  Phalaris arundinacea 'Big Medicine' because it's my understanding that it is high in desirables and low in undesirables.

Grass from seed is often reported to be less "potent" than clones of known potent grass strains.

Best of luck everyone.