You did a nice job. Regarding the wire brushing, you have to wire brush 24 to 48 hours after it sets up in the mold. It's too hard to do if you let it set up longer. For most planters/troughs I unmold and wire brush in 24 hours, wrap back up in plastic for a couple of days and then put it in a water bath for a few days. You do not have to dry slowly over the Summer. Unless the alpine plants are sensitive to lime you should be able to plant right now. The soil usually buffers the plant from the lime in the trough. You didn't use any sand? What did you use for an outer mold? Did you use an inner mold?

Outer mold was just some plywood. No inner mold. I put some screws through the boards to indicate the proper tufa depth. The brush scratched the surface rough enough to me liking, but not very deep. No sand in the mix. Too heavy. I can't plant until the spring anyhow since the new catalogs don't come out until March 2016...

Nice. I have made some as large and even larger. Good job.

I have never used an inner mold, by the way.

Looks great! It will be really neat when it fills in

This is just beautiful. I love the size and the way you planted it. I am really into the big ones lately. Yours is great.