Fresh ivy is lovely in all wedding work, including corsages and boutonnieres. I suggest you temper ivy by soaking it in a tepid bath of water for about 20 minutes before designing with it.
Cut the ivy into small pieces and wire individual stems for each. Bend the wire into a hook and place over a spot where the leaves join the stem.
Pull the wire down taut and tape into place.
Use fresh floral tape in either light or dark green.
Now the ivy can be bent and manipulated to curve around flower heads.
I always spray my fresh greens with a flower sealant such as Leafshine. This seals the leaf, locking moisture in and giving the cut leaves maximum life.
Always allow the spray to dry before refrigerating.
Place your wired greenery on the foam block along with the roses previously wired.
If fresh ivy isn't available, you can use silk. Look for tiny leaves on a wired stem for the most realistic look.