Use these helpful tips for growing and caring for your own batch of canna plants. Cannas are an unusual member of the plant world because they are only remotely related to any other plant family. The canna has its one plant family, Cannacaea, with only one genus, the canna itself. It is a tropical herbaceous plant, with origins ranging from Florida to the warmer parts of South America. This plant is one of a number of tropical plants that have large leaves that open by unfurling. Its common name is Indian shot or Canna lily. It is known for its colorful foliage, sometimes multi-colored, and spectacular flowers on tall stalks. The flowers grow on stems from four to six feet tall, can be up to five inches across, and resemble gladiola flowers. Leaves, while primarily green, can be bronze, purple, or have purple veins running through them.
The plant was popular for 4000 years with indigenous American peoples. They ate the rhizomes and used the broad leaves for many purposes. The rhizome tastes like sweet potatoes and was once a staple crop in South America. It is still grown in Asia for use in making cellophane noodles.
Plant your canna in full sun and moist soil, in a spot sheltered from the wind. The plant is hardy in USDA zones 8 to 10 but can grow in slightly cooler climates with extra care. Rhizomes are planted in the spring in warm soil after the last frost-free date. Till the soil to 12 to 15 inches and work in two to four inches of compost. Dig holes four to six inches deep and about one to four feet apart. Set the rhizome in the hole horizontally, cover with dirt, and press firmly. Cannas like to grow in groups so you can place three rhizomes fairly close together then set another grouping at least a foot away. Water well. If you live in an area with short summers, you can start the rhizomes indoors and grow in a sunny window.
Cannas are tropical plants and like moist soil. Mulch well with two to four inches of mulch to retain moisture and fight weeds. If you get less than one inch of rainfall per week, water your cannas well every week. Fertilize monthly with a balanced fertilizer (10-10-10) and deadhead spent flowers. With proper care, cannas will bloom right up until the first frost. Taller plants will do best if staked for support.
In the fall, the initial rhizome will have multiplied and will have four to eight "daughters." Dig up the entire clump after the first frost, along with some of the soil surrounding it, and store in a large pot or box filled with peat or perlite. Do not divide the clump at this point and do not allow clumps to touch each other during storage. Store off the ground in a dry area at 45 to 50 degrees and replant in the spring. When you are ready to plant, you can divide the clumps.
Cannas are susceptible to rolling leaf caterpillars, slugs, snails, and viruses so keep an eye out and remove any pests or diseased plants. Plants affected by viruses should be dug up and destroyed. In the spring, new shoots should be sprayed for aphids. With these protective measures and proper care, your cannas will bring height and color to your outdoor space.