I have an Alyssum border from a couple of years back. It’s not in bloom yet. If I just trim it back with scissors, will it bloom again? I don’t want to destroy the plants. I’m in the San Francisco Bay area – very mild climate and the frost is probably over now.
You can trim the damaged or dead parts of the plant but do not prune until after it's first bloom.
After blooming you can trim the plants back to half the height.