Originally posted by GunsForBucks:

Stone flooring will cover them.
I kind of like that they can't be destroyed... some things you might think you have enough of may end up in short supply later due to new recipes.

had a stone floor in the basement of a fort in black forest (The basement was built a good deal of time after the base , was surprised it worked) Had a single thistle that would always spawn between the cracks. no mods.