Canna lilies: An American plant

Canna lilies introduced themselves to me in the spring of 2016, my first year in Hendersonville. I was contemplating my small yard, wondering how I could plant everything I wanted.

As the weather grew warmer over the course of a few weeks, fascinating plants rose up from the fertile ground all by themselves. Thinking they were a tropical plant, I didn’t realize what they were until I saw one in an arrangement at a local nursery. Canna lilies!

They grew fast, reaching heights of six feet and more. But they didn’t grow straight, were very crowded and didn’t produce flowers. I’d rather have my canna lilies look like the yellow ones at our Extension Office, or the bright red ones in front of Hendersonville High School.

Thus began my intervention and my continuing, mostly happy, relationship with canna lilies. My first effort was to thin the lilies by cutting them down to ground level. That only caused more to grow, so I dug up a root which sparked my interest in cannas anew.

The roots are called rhizomes, rhizomatous or swollen underground stems. Rhizomes are subterranean plant stems that grow horizontally and send out roots and shoots from their nodes. Rhizomes also have the ability to allow new shoots to grow upward. Some that I dug up were indeed growing horizontally and sending out shoots. Many others grew vertically and ended in clusters of nodes which each became an individual shoot, looking almost like bulbs. I wanted to make a new bed of “managed” cannas that would grow straight, have their own space and produce flowers.

I selected four or five root segments that each had two to three nodes and planted them two feet apart. My cannas didn’t disappoint. In fact, they surprised me again by each segment producing its own seven to eight stalks. They were crowded with two flowers at best. I decided to let the cannas have their own way and do what they wanted. Time will tell what they decide to do this year.

Aside from my experiences, I found that cannas have stories of their own that merit interest. They are not true lilies. Liliaceae is the family of a true lily and its genus is Lilium. Canna belong to the family Cannaceae and its genus is Canna. Canna is the only member of the Liliopsida class in which hibernation of seed is known to occur, due to its hard, impenetrable seed covering.

Although cannas provide garden enjoyment, nature intended them to attract pollinators. The pollination mechanism is highly specialized. Pollen is shed on the style while still in the bud. In some species of canna and early hybrids, some pollen is also found on the stigma because of the high position of the anther, which means that they are self-pollinating.

I’ve noticed nothing more than a few Japanese beetles on my cannas. However, they are susceptible to several pests and diseases.

One disease is canna rust, a fungal infection. Symptoms appear as yellow to tan pustules on the foliage and stems. The pustules release large amounts of spores which cause the infected leaves to dry and drop prematurely. The fungus may also affect the blossoms of the canna. As the name implies, if you wipe a finger over a leaf with pustules, you’ll have a rusty brown stain.

To prevent canna rust, plant the canna in full sun and allow for plenty of air circulation. If fungicides are called for, use copper products according to the manufacturer’s instructions.

Commonly called achira in Latin America, cannas have been cultivated by Native Americans in tropical America for thousands of years. They are one of the earliest domesticated plants in the Americas. All canna species that have been introduced to Europe can be traced back to the Americas. It can be asserted with confidence that canna is solely an American genus.

Therefore, next time you pass a canna, don’t forget to salute!

This information is provided as a service of the Henderson County Extension Master Gardener Volunteer program. Do you want to learn more? Contact a County Master Gardener at 828-697-4801 or hendersonmgv@gmail.com.