Answer: It won't hurt your Cannas at all to remove the spent flowers and stalks. Try making a clean cut just below the tops of the foliage, but don't cut the foliage down until the end of the season. Removing the spent flowering stalk will divert the plant's energy into maintaining the foliage, and your plants will look much neater!
If cannas are stressed for water, especially while the flowers are forming, the leaves will turn brown.
Cannas bloom best when grown in full sun and well-drained, humus rich soil. Water them regularly and deeply, so soil is consistently moist. When the rhizomes become overcrowded, they will stop blooming. Spindly stalks are a sign of overcrowding. Actively growing cannas may need to be divided every three to four years.
As the foliage withers and dies at the end of the season, cut it down to soil level and mulch over the bed with organic matter. If the foliage is persistent, cut it down to the ground in October or November and mulch the bed. The plants will develop new foliage during early spring.
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