Canna lilies (also called cannas) are spectacular and very easy to grow. However, canna lilies are not for the faint of heart. They are generally huge with large showy flowers, and when you grow them, you are making a visual statement with an exclamation mark. Cannas work well in pots and can be transplanted indoors or out, using the plants' rhizomes (underground roots). The rhizomes can also be stored for winter.
Canna leaves are the show stoppers--wide and long, they can have a wild stripe pattern, and their colors can range from yellows to oranges to almost black and neon pink. Watching canna leaves shoot up and then unfurl over a few days is miraculous. It's one of those gardening experiences that is both moving and poetic.
When and Where to Grow Cannas
Cannas are easy to plant, both inside and out. If you live in a climate that is zone 7 or warmer, you can grow cannas outside year-round. In you live in a cooler climate, you can either grow them inside in pots or you can plant them outside during the warm months and, when winter hits, cut off the plants' rhizomes and bring them inside, where you can replant them in pots or store them for winter.
To store the rhizomes, shake off the soil and keep them in a damp medium in a cool (frost-free), dry place.
Cannas are large plants, so bigger is better. Choose a pot that is at least 15-18 inches in diameter. This is not only for aesthetic reasons; it also increases your chances for large healthy plants, and it prevents the pots from tipping over.
Planting Cannas in Pots
While it is possible to buy plants that are already growing, it is common to grow cannas from the rhizomes. To plant the rhizomes, place them 4 inches below the surface of the potting soil, making sure there are no air pockets and that they are surrounded by soil.
If you live in a cold climate (less than zone 7), you can start your cannas inside and move them outside once the overnight temperatures are consistently above 50°F.
Caring for Cannas
While cannas prefer full sun (6-8 hours of direct sunlight) they will survive in partial sun (4-6 hours of direct sun). They prefer to be kept on the moist side and don't like to dry out completely. Cannas need to be fertilized regularly, with either a slow-release fertilizer or a diluted liquid fertilizer.