If you wish to make a corsage that is pinned on the wearer's shoulder, wiring the individual flowers and decorative components (such as ribbon, tulle, greenery etc.) is the most common way.
Roses are prepared for corsages by pushing a thin wire through the calyx (bulb) of the flower head and bending down to form a new, more slender and flexible stem.
If you were to simply tape the flowers together using their original stems, it would be very stiff and unflexible, resulting in a thick and unwieldy stem.
Use professional floral tape, winding it high under the flower head and pulling in a downward motion. This causes the tape to stretch and adhere to itself.
Be sure to buy your supplies from a working warehouse or floral supplier. I was in town for a friend a few summers back when she asked for help in creating some corsages and boutonnieres for a local wedding. She had purchased her floral tape from a $1 discount store.
It was a mess! The tape was sticky, gooey and made the job so much harder. Floral suppliers have a regular turnover of their products - which do sometimes have a shelf life. "Bargains" may not always be as great as they seem!