You may remove dead or damaged leaves and spent flower stalks (not just the flower heads) at any time.
I trim back anything raggedy, leaving the green parts.
if they seem very crowded, you may have a need to lift, divide the rhizomes with a sharp knife and replant, spacing them out, or passing them along to others. Best to replant within a couple of days.
They benefit from spring fertilizing, and again in mid-summer. Osmocote (in spring) works well for bloom production, Milorganite (in summer) helps keep them greener after blooming.
They 'rest' in fall and winter, but still absorb sunshine for energy through their leaves for next year's blooms, so don't cut them back.
Happy Gardening!
|