Scabiosa is also called the pincushion flower because of the padded appearance of its domed blooms. Scabiosa is a perennial that grows to about one and one-half feet tall and wide and prefers full sun with shade in the late afternoon. You can prune scabiosa to prolong the duration of other blooms on the plant, to produce a fuller plant, to clean up the plant in the spring or to winterize it.
Cut or pinch off the dead blooms. This measure to prune scabiosa will send plant energy to other blooms to sustain their bloom time. Use pruning clippers for this task, or grasp the stem in your fist just below the deadhead and use your thumb to push off the deadhead.
Prune scabiosa down to the crown (just above ground level) if the stems fail to branch out. You can do this pruning any time in the spring or summer after the plant reaches about one foot tall. By that stage of growth, you can more clearly see if the stems are maturing as they should with multiple branches. When the plant grows back, it will be fuller.
Prune scabiosa down to the basal foliage (the leaves that grow around the crown of the plant) if the plant has just one center leader (like a trunk). The single central leader can occur after years of growth of this perennial plant. In early spring when the plant first starts to grow, you should be able to see if it needs to be pruned down to the basal foliage. After pruning, your scabiosa plant will grow back fuller.
Prune scabiosa flower stems off in late fall just above the basal foliage.
Cut off any dead portions of the plant in early spring. This pruning at the beginning of the season is not for growth purposes but to make the plant look prettier.