Some of my Dusty Miller leaves for this DIY boutonniere needs a longer wire because of the size of the leaf. Before taping the wire, pierce the central stem of the leaf in the back with the wire.
Bend it down parallel with the leaf central stem.
I wrapped the small part of the leaf at the bottom around the wire.
This isn't necessary if your leaf looks fine without doing this.
I then tape the wire into place with floral tape.
Place the wired leaf against the back of the rose and check placement before taping into place.