And they were spraying all kinds of nasty shit...

Yes they used literal shit, both animal and human.

...on grass that isn’t native...

I can't answer that but it really wouldn't surprise me. The ruling class commonly imported plants and animals from all over the world.

...to make it look pretty?

No pictures exist, obviously, but I'm quite sure that groundskeepers were doing whatever was necessary to make their Lords estate look as good as possible.