Here’s what you need to know about deadheading perennial flowers. The rules of thumb here depend on where the flower originates within the plant. If at the base of the plant such as Hosta – then the entire stem is cut off right to the ground. If part way up or at the top of a stem such as with an Echinacea, then you take the stem and “perhaps” a bit of the main stem and leaves with it. It’s not rocket science and if you make a mistake, nothing is going to happen. (well, your plant might look a bit ugly until it regrows to fill in but that’s about it) You won’t kill a plant is you take off a few too many leaves or a stem here and there.