I would hope so since they ARE a fertilizer distributor.
Several years ago I used some grout for the parking lot at Heavy Metal and was pleased at how it looked, much finer than any commercial made gravel.
When I was planning Gavilon I wanted to use grout again, but this time I thought I'd use more of a white color to represent limestone. I found a good color from Blowes called Frost. It was almost white and figured I could tone it down with a grayish wash.
Today I got the itch and was able to get the grout down at Gavilon. It was white that's for sure but was able to tone it down using some gray and brown craft paint that I mixed into a small spritz bottle so I could spray it on rather than brush it on as I was afraid it might not go down even and I'd see the overlay.
Once it dried for a few hours I started adding ground foam for the first layer of weeds.
You can see that it's just a bit Off-White and if you look close you can see where the glue leached into the grout when I glued the weeds in place. In time I think I'm going to try to play with some weathering powders to highlight different areas where the limestone has sunk into the mud?