Using a piping bag, fit with Tip 104 petal tip, pipe the center of the rose. Make sure to hold the bag with the fatter end of the tip down. Tilt in slightly so that a small curled cone is created as you spin the nail and squeeze the buttercream out of the bag. This forms the tight bud in the center of the rose.
Using an arched or rounded motion as you pipe, pipe 3 petals around the center of your flower for the first round. Hold your tip straight up and down as you pipe the 3 overlapping petals. The top of the petals should line up with the top of the center of the rose.
Pipe another round of 3 petals. I like to pipe two rows of 3 petals, and then add other rounds of petals as they fit in naturally. A general rule to follow is to pipe odd amounts of petals for each round(3,5,7). You can do this if it works for you, but sometimes counting the petals ends up giving you more of a headache and awkward rose than if you just let yourself pipe around it naturally. I'm more of a free spirit and like to see it form organically! (=
Once you have the desired fullness of rose, you need to move it to your cupcake! With a pair of scissors slightly open,carefully slide them under the buttercream rose. Glide the rose off of the pastry nail and onto the cupcake. The scissors should slide right out from underneath it, but if you have trouble you can use a chopstick to gently hold the rose onto the cupcake as you pull the scissors away.
If you want to cover the entire cupcake with the rose, pipe a few petals around the rose until you acheive the look you want. For a simple and sophisticated look, keep the basic rose, and maybe add a sprinkle of edible luster dust on top.
Use a star tip to add some details in a complimentary color around the roses for a more shabby chic look.
Add a thin line of a complimentary color food coloring down the inside of a pastry bag (leading to the thin point on the 104 petal tip), before you fill the bag with your butterceram. The result is a rose with more dimension and interest. The extra punch of color along the edges of the flower really make it pop!
There are lots of 'rules' to piping buttercream roses. I think that all flowers are unique, and so are all people. Once you know the basics of the technique, you can find how to make the style of rose that fits you. Don't be afraid to scrape off your frosting and start over again, that's part of the process! I like to pipe my roses directly on my cupcakes now, because I have more control of the size of the rose and sometime the roses on the pastry nail end up being too much frosting for the small cupcake. The cupcake is harder to spin than the pastry nail as you pipe, so make sure to practice on the pastry nail first to avoid getting frustrated. (= Also, don't stress about doing it 'right', have fun, practice, and please share your beautiful rose creations with me!