Since I was working on a deadline and didn't have the usual petal and leaf cutout set made especially for these types of projects (because it wasn't handy in my town), I had to improvise and used the flower cut-outs.
Always remember that fondant dries out, so only work with a small bit at a time, and keep the rest wrapped up tight in plastic wrap to prevent it from drying out too quickly. I rolled out enough to cut six to eight pieces at a time. Also, since I don't have a fondant rolling mat (they can be nice, but really aren't necessary) I used corn starch on the counter and rolling pin to keep the fondant from sticking. This was before I started using shortening on the counter instead--which is really better for me since the corn starch dried out the fondant too much.
I used the large cutout from the set and for the first row of petals cut out every-other petal.
This picture is really bad, but you can see I ran the toothpick through the cut piece, then wrapped it around the tip. Once I had the shape I wanted on the top petals, I pinched off the base part so the second set of petals would be even or nearly even with the inner row.
This is the second row of petals. I cut out one petal from the shape and added cut lines between the petals so they could overlap each other. When I slid it onto the toothpick, I also used a clean paintbrush from a kids' watercolor set that I bought just for fondant. I brushed a thin layer of water over the petals where they would overlap. Fondant will stick to itself easily with a touch of water. Be careful, though, not to let water drip on any parts that are going to be seen on the outside as water will leave marks behind on the surface.
For the third row I didn't cut any petals out, but still split the space between the petals. Then I took a toothpick and separated the petals and curved them back slightly to give them a little more realistic look. This really works best if you use thin pieces of fondant. These were rolled to 1/8 inch or thinner, but there may be some times when slightly thicker pieces will work fine.
If you're going to have roses, you obviously need leaves! Again, there were no cutters for leaves in stock, so I used the edge of a glass to cut each edge. If I had to do it again, I would have used a round cookie cutter because the glass didn't leave a crisp edge and they had to be trimmed with a knife to clean them up.
Next I used a toothpick to draw lines on the leaves.
Then I set everything out to dry since I made them several days in advance of the cake. Be aware that some colors fade a lot when the fondant dries. The pink faded to way less than half the original brilliancy as it dried, while the leaves only lightened a little bit.
A few days later I baked the cake, frosted it (crumb layer, then an outer layer), and rolled the purple fondant. Once that was ready, I used the toothpicks on the roses to stick the roses in the cake where I wanted them. If needed, they could have been cut off or trimmed back, but they were handy to create the design I was looking for.
The first of the small flowers were attached to the bottom of the cake with buttercream icing.
Then I used yellow buttercream to put dots in the flowers and the roses.
With a little extra playing, I finished up with the little flowers, tacking them and the leaves onto the cake with more buttercream. The green stems on the roses are also buttercream piped on with a small round tip, probably a #7. A slightly smaller circle tip, like a #4 made the dots in the flowers.
This cake was made using 2-8" round pans and it fit perfectly in one of these boxes. It was a hit!