Getting Started with Cannas

Canna Yellow King Humbert

Yes, you can – grow Cannas!

Cannas are tuberous plants with colorful tropical looking foliage and brilliant, lily-like flowers. The leaves may be green, yellow, purple or multi-colored with stripes, marginal markings or blotches. The flowers come in colors of white to ivory to shades of yellow, orange, pale to deep pink, apricot, coral, salmon and a variety of reds.

Their common name is Indian-Shot. This refers to the plant’s black, very hard seed, which resembles the shot or pellets in shotgun cartridges. Cannas come from tropical and subtropical areas of the Americas and Asia. They are easy to grow, both in the ground or in containers. They can be grown from seed or by saving the tubers from year to year. The leaves may be used in flower arrangements. The flowers only last a day to two, so, do not make good cut flowers.

There are three main types of cannas: lower growing and dwarf varieties include the French or Crozy cannas which grow 3-4 feet tall, with large flower trusses; the Pfitzer Dwarf cannas from Germany, which grow 2 feet to 3 feet tall; and the Seven Dwarfs series which only reach about 18 inches. The Italian, or orchid-flowered cannas, are tall 4-5 feet, and the flower segments are more open and spreading than the French cannas. The third group includes all the other cannas, most of which are the tall, 5-6 feet, old-fashioned varieties with smaller flowers and large leaves.

Because of their tropical look and lush foliage, cannas look great when planted against a plain background and in groups of a single color. They make striking poolside plantings and look great around or in containers on terraces, patios or decks. They are great mixed with hot colors in a perennial border. They go well with tall grasses. Cannas bloom continuously and look good all summer, even through the dog days of August.

Cannas were used extensively in the Victorian era as they lend themselves well to bedding out schemes and formal gardens. For a taste of this type of planting go to Skylands in Ringwood in August or September and look at their annual garden. It is very Victorian. More recently bedding out schemes had lost favor as had bold colors and tropical foliage. The style of 30 to 10 years ago was cool colors, pastels and perennial borders. The pendulum has swung back the other way now, and bold colors, foliage and the tropical look are back in. These combinations are being used in a more informal manor and usually thickly planted for a lush look.

Although cannas may be grown from seed, usually the seed will be mixed colors and sizes, so what you get may not be what you want. Seeds may be started in early spring. Nick the seeds with a file or knife or soak in warm water overnight to hasten germination. Plants need to receive good light and may be planted outside in late May.

If you buy rootstock, you will be assured of getting what you want both in size and color. Rootstock may be started indoors in early April for a late May planting. Start in flats or pots with bottom heat and keep them warm until they sprout. Afterwards supply them with good light for strong growth. Or plant them outside in the spring. Cannas are hardy to Zone 7, so they can take some cold. Here at the Arboretum, we often plant them outdoors in early May. They usually take a few weeks to really come up but the root system is establishing itself during that time. Plant them 4-6 inches deep, 10-24 inches apart (depending on cultivar).

Cannas love rich lose soil with all the fertilizer you can give them and as much heat and sun as possible. Keep them well watered at all times. Pick off faded flowers to prevent seed production and when the stalk has finished blooming, cut it down completely to the ground.

If you live in Zone 7 (shore) or plant you canna right by the foundation of the house, it will be hardy outdoors. If you have a lot of rootstock available, you might try leaving some in the ground over winter and mulching heavily. Some cultivars are reported to be more hardy than others. Otherwise, you must dig them up in fall, after a frost has hit. Lift them out of the ground with a fork and shake off the soil. Leave them outdoors for a day to two if possible to dry off. Store the rootstock in brown paper bags, open cardboard boxes or burlap in a cool, but not freezing place. An unheated attached garage or cool basement works well. At the Arboretum, we store ours in a cool hoop house still in their containers and watered occasionally. Others are stored out of a pot in a cool cellar. Check the roots occasionally to make sure they are not drying out too much. Spray a little water on them from time to time if needed. The next spring bring out the rootstock, and divide as needed. Leave at least three eyes to a division and more if you like. Container grown ones should only be a small division, especially if you plan to plant something else in the container.

Cannas do well as a single item in a container or may be combined with other tender annuals. Be sure to pick items of approximately the same size as cannas grow quickly and can easily overwhelm other plants in the containers. Perhaps you will choose to use tall, fast growing coleus as a foil in the containers.

Cannas have few pests or disease problems. Occasionally European Corn Borer may attack the stalks in last summer or early spring. The larva is pink, 0.75 to 1 inch long; the egg-laying moth is yellow-brown and nocturnal, thus hard to spot. If you find this borer, kill it, and try to get the larva out of the stalks. But Japanese Beetles will often be attracted to Cannas in July. The adults the congregate on the leaves, mating and feeding. Every evening go outside and had pick them off. Remove badly damaged foliage. Most sprays do not work well on Japanese beetles.

When planting in containers, use Pro-Mix, mixed with compost, Osmocote and one of the water absorbing products on the market. Cannas are very thirsty and quickly dry out. By using this substance, you will be able to water every other day. The Osmocote provides time-released fertilization all season long.

Good luck with your Cannas!