|Only having just discovered that my alyssum will come back, I don't know whether to cut back the old growth now and, if so, how far?|
|Annual alyssum can reseed and come up again the following year. This year's plants should be removed after they set seed. During the growing season, if you cut back the spent flowers, you can keep the plant blooming through the summer. At the end of the growing season, allow the flowers to mature and produce seeds.
Perennial alyssum should be cut back after bloom. Remove the spikes of spent flowers plus some of the long, straggly stems to keep the plants neat and compact during the growing season.