Should Agastache be cut back in the fall?
Pruning and deadheading: Agastache is an herbaceous perennial plant that will die back to the ground in fall. Cut back dormant stems to half their height to protect from winter winds. In late winter or early spring, cut the remaining stems back to the ground before plants break dormancy. Trimming & Pruning: Trim back Agastache plants by pinching the new growth in spring to promote bushier growth. Deadhead (trim) spent flower stalks to keep the plant tidy.Deciduous shrubs should be pruned in winter, particularly those that grow too big for their allocated space. Renovation pruning will revive plants that can become large and unproductive, such as cotinus, berberis and flowering currants.
Will Agastache spread?
Agastache Spacing It spreads mainly by self-seeding late in the summer. These seedlings are easily removed and can be replanted in a more desirable location early in the spring. Often early in the spring, the new emerging shoots of Agastache will appear ragged or uneven. The telltale shiny slime trails left by slugs will be visible during the day as well as other damage to tender shoots. The good news is that once the plants have grown to 6 inches or more, slugs rarely present a problem.