Growing Cannas is a little like bringing a piece of the tropics to your own garden. If you live in USDA growing zones 8-10 than Cannas can be treated as perennials but for the rest of the country they must be treated as an annual flower. Cannas, as you would expect from a tropical plant, are very sensitive to cold temperatures. A frost will kill the foliage above the ground and a cold snap where the ground freezes will kill the plant entirely. For these reasons, in most of the country Cannas should be planted after all damage of frost is past. In many places in the U.S. this is around Mother’s Day but in the Upper Midwest and Northeast this could date could be as late as Memorial Day but Cannas can also be planted in containers to get an earlier start on the growing season.
When planting Cannas it is important that the soil be consistently moist. They should be planted at a depth of 5 to 6 inches and mulching is a good way to maintain these soil conditions. Cannas thrive in garden beds that receive full sun for most of the day but will tolerate some shade. While most Cannas will grow 5 to 6 feet tall they never need staking or other supports and the last few years have seen the introduction of new varieties that have been bred to only grow 2 to 3 feet tall. This trait makes these Cannas ideal for pots and containers. Cannas bloom 8 to 12 weeks after they are planted. This means in most places they bloom later in the summer through the fall. New colors are being bred each year and they come in variations of yellow, red, pink and orange. Fortunately, while we are waiting for these beautiful flowers to bloom they have attractive foliage like a banana tree that come in colors like green, maroon and newer varieties even have variegated foliage.
During the growing season Cannas really do need a minimal amount of care. They rarely have problems with insects or diseases and will bloom until cold weather stops them as long as the spent flowers are removed. This process, known as deadheading, channels the plants energy into producing more flowers. The fact that Cannas love the heat means they start to take over your garden when other flowers have already finished blooming. This gives your garden a boost of color just at the right time. If all of these benefits don’t make them worth growing Cannas have one more feature that makes them an attractive addition to your garden. Although they are considered annuals in terms of their bloom cycle, it is possible to harvest the Canna tubers and store them over the winter and plant them again the next year.
Once the foliage has died, usually after the first frost, remove the foliage leaving about 4 to 6 inches of stem above the soil line. Dig up the tubers, rinse the soil off and then allow them to dry out for a day or two. You can then put several tubers in a plastic grocery bag and add either peat moss or a moist paper towel to the bag. Store the bag in a place that maintains temperatures between 40 to 60 degrees to avoid freezing or the formation of mold. Simply check the bag monthly to see if a little more water is needed and you are ready to plant them again in the spring. Cannas may seem like they are difficult to grow because they are a tropical plant but the truth is they are suitable for any gardener, including you!