Since you change those buildings out, you could put some loose shrubbery pieces around the edges of the buildings for weeds.

I’m glueing very little shrubbery and under growth down on my layout since it is coming out in two years. I’ll be able to save most of it. Same thing with the tree lines along the wall, they are foam boards painted green with foliage applied, just loose leaning agsinst the wall. They will get reused on the next layout too.