Answer: The flower stems should be trimmed off when all of its flowers have wilted. You may also remove individual blossoms as they fade if you wish, but this can be time consuming.
The foliage should be left in place until later in the season when it begins to yellow and droop. Then it can be trimmed off by about halfway. (Any diseased foliage should be removed immediately.) The foliage is important in building strength in the rhizomes, so it is best to keep it growing. Routine care would also include removing spent or discolored foliage in both late fall and early spring, this is important for disease prevention.
Q&A Library Searching Tips