I'm having trouble making roses with smooth petals. The petals come out with jagged edges and look more like carnations
I'm using a basic BC recipe. If I thin down the BC, they end up slumping over - too soft. Could my tip need to be opened up at the end? I know the leaf tip needed it...
I have had this with a lot of my students. Most times, it is the consistency of your frosting. I would try adding a "little" bit of water at a time, beating well after each addition.
You definitely don't want to thin down your icing, as you have already discovered.
Use a teaspoon of piping gel per cup of stiff icing to smooth the jagged edges of your rose petals. Also, make sure you are using ample pressure. Most of the time with my students, the jagged edges are a result of not using enough pressure while squeezing (because I give them instructions to use piping gel in their stiff icing for class).