Collect the silk flowers you want to use. Try a few different arrangements and colors together until you get your desired effect.
Trim the stems to your desired length. Scissors should work
Use floral tape to secure everything in place. Floral tape can be finicky, but if you take your time, you should be able to wrap it around and secure the flowers without too much trouble.
Use a pretty ribbon to cover up the floral tape. Use a hot glue gun.
Add a florist's pin and you've made a silk flower boutonniere!
Take a watch and enjoy!