The Canna Lily, with its enormous, paddle-shaped leaves and flamboyant, iris-like blooms, brings an immediate sense of the tropics to any garden. These plants are prized for their vibrant foliage, which ranges from deep green to bronze and variegated stripes, and their continuous summer flowering. Gardeners often seek to add this dramatic flair to their landscape, but wonder if the plant will return year after year. The answer depends entirely on the climate where it is grown.
The Definitive Answer: Perennial vs. Annual
Canna Lilies are botanically classified as herbaceous perennials, meaning they possess the genetic ability to live for more than two years by dying back to the ground in winter and regrowing in spring. They are a tropical species that grows from underground storage structures called rhizomes. The perennial designation depends entirely on the plant’s ability to survive the winter temperatures of a specific geographic location.
The critical factor is the rhizomes’ inability to withstand freezing temperatures. For gardeners in USDA Hardiness Zones 8 and warmer, the Canna Lily can remain in the ground year-round as a true perennial because the soil does not freeze deeply enough to destroy the rhizomes. Outside of these zones, where temperatures regularly drop below freezing, the plant is functionally treated as a tender annual.
Caring for Canna Lilies in Warm Climates
When Canna Lilies are grown as true perennials in warmer regions, maintenance focuses on maximizing their vigorous growth and prolific blooming. They thrive in full sun, receiving six to eight hours of direct sunlight daily, though afternoon shade is beneficial in the hottest regions to prevent leaf scorching. The plants are heavy feeders and moisture-loving, demanding rich, consistently moist, and well-draining soil.
Regular fertilization supports their growth and continuous flowering until the first frost. Applying a balanced, slow-release fertilizer in early spring, followed by liquid feeds every four weeks during the growing season, promotes robust foliage and flower development. Routine deadheading, the removal of spent blooms, is also important to redirect the plant’s energy away from seed production. In the fall, after the foliage has browned following a light frost, cut the dead stalks back to a few inches above the soil line to prepare the plant for dormancy.
Overwintering Canna Lilies in Cold Climates
In colder climates, where the ground freezes solid in winter, Canna Lily rhizomes must be lifted and stored to prevent them from dying. The process begins after the first hard frost, which causes the foliage to blacken and signals the plant to enter its necessary dormancy period. Cut the stalks back to approximately six inches above the soil, leaving a manageable handle for lifting the clump.
The entire clump is then carefully dug from the ground using a pitchfork, taking care not to puncture or bruise the brittle storage organs. After lifting, shake off excess soil, and allow the rhizomes to cure in a warm, dry, and dark location for several days. Curing toughens the outer skin and reduces the risk of rot in storage. Once cured, inspect the rhizomes for damage or disease, and trim back the long, fleshy roots.
Storage Requirements
For storage, the rhizomes require a cool, dark environment where the temperature remains consistently above freezing, ideally between 40 and 50 degrees Fahrenheit. They are typically packed in a breathable medium like slightly damp peat moss, vermiculite, or sawdust. This helps maintain a stable, slightly humid environment without excessive moisture buildup.
The rhizomes should not touch one another during storage to minimize the spread of mold or rot. Periodically check the stored rhizomes throughout the winter for shriveling or decay. They can be replanted outdoors in the spring once the soil temperature consistently reaches about 60 to 65 degrees Fahrenheit.