I don't know if your silk flowers are actually that fiber, a blend, or all synthetic.  If either of the last two, I have been able to cut shapes with a heat tool that I got at Michael's.  It may go by several names, stencil burner being one.  I use the stencil burner tip, and work on a piece of glass.  Keep the tool moving smoothly to avoid blobs of melted material.  Good ventilation is a must.  Hope this helps.