Apply your taped salal leaf directly behind the head of the rose. The tip should show over the flower head as shown.
Wiring the leaf allows you more control. You can actually bend it forward a bit so it cups firmly around the rose head.
Now I'm placing a second wired leaf behind the first, slightly lower and to the right of the rose. Tape into place.
I do the same with another leaf on the opposite (left) side. Notice how I've taped the leaf deliberately so that it cups snugly around the rose head.
You can see from the back that the leafs are surround the rose like a continuation of the way rose petals cup around the flower head.