As flowers fade, you can trim them off to keep the plant neat, but you don't have to. Nemesias are self-cleaning. ... When you do choose to deadhead, use scissors or plant shears that you sterilize with rubbing alcohol or household antiseptic cleaner, and snip off the flowers either individually or in clusters.

Do Nemesia need deadheading?

Deadhead to encourage more blooms. If you want to keep your perennial nemesias to flower the following year, move them to a frost-free spot to overwinter.

Should I prune Nemesia?

About Nemesia Trimming

Nemesia prefers to be grown in well-drained soil in full sun but the blooms last much longer in hot climates when the plant is grown in an area of afternoon shade. ... The good news, though, is that while Nemesia doesn't need to be pruned, trimming back Nemesia will likely gain you a second bloom.