Canna Growing Guide
Canna (Canna spp.) is a tropical perennial flower native to the southeastern United States through southern Texas and south to northern Argentina and will do well in USDA Zones 7 to 10.
It should be planted in full sun to light shade. In colder areas it is planted in the spring after the last frost and the soil has warmed up. It is a rhizomatous herbaceous perennial plant. A rhizome is the underground stem that produces both roots and shoots.
Although it is sometimes called Canna lily, is not a true lily. It is in the genus Canna and the family Cannaceae.
Most standard varieties are tall and grow 4 to 6-feet tall and need to be placed at the back of a flower bed. There are some dwarf varieties that grow 2-1/2 to 3-feet tall that will look good at the center to the rear of the flower bed.
In addition to being deer resistant, hummingbirds, butterflies and pollinators are attracted to the beautiful flowers, which may be in various shades of red, pink, apricot, cream, yellow or orange.
The beautiful foliage will also add a lot of color to your flower garden. The foliage can range from green to burgundy as well as some stunning variegated colors containing green, gold, rust, pink and burgundy. Look through the packages in the garden center and you are likely to go home with several varieties.
Starting from Seed
If the spent flower is left on it may produce seeds. After the flower dries the seed pod begins to grow larger as the seed embryo develops. The seed pod may contain 1 to 3-seeds and should be left on until it dries and starts to split. At this point the black seeds have matured and will be about the size of peas. Put the seeds in a small envelope to save for planting in the spring.
The seeds have a poor germination rate due to the hard outer coat. To improve the germination rate we can scarify the seeds by weakening the hard outer coat. To do this, take a piece of medium grit sandpaper and lightly sand one or two areas just enough to get through the black seed coat and the white endosperm just starts to show. This will allow moisture to penetrate and germination to occur.
Plant your seeds 8 to 10-weeks before your last frost date a quarter-inch deep in potting soil in trays or pots. It may take 20 to 40-days for germination to occur.
For more detailed information visit the seed starting page.
When the seedlings reach 5 to 6-inches tall they can be transplanted into individual pots with good potting soil. After the last frost date and the soil warms up, the seedlings can be hardened off and planted outdoors.
Most cannas are hybrids and are usually propagated by division to remain true to their variety. Growing seeds from hybrids will usually look different from the mother plant.
Soil Preparation
Plant your canna in full sun to light shade in a nice loose well-drained garden soil. The rhizomes can rot in poorly drained wet soils. As soon as the soil is frost-free and can be worked, till the soil by digging down 8 to 12-inches turning the soil over with a garden fork.
Remove any large rocks and stones. The small stones remaining will do no harm and actually benefit the soil by adding some micronutrients to the soil. Canna will do best in a slightly acid soil with a pH range of around 6.5.
Planting
Canna should be planted in the late spring after the last expected frost and the soil warms up.
Plant the rhizomes 12 to 24-inches apart 4-inches deep with the eyes pointed up. If a shoot has started to grow it can be level with the ground. Plant them in groups of 3 or 5 behind other shorter plants.
Watering and Care
Canna are low maintenance and easy to care for. All you need to do is add a layer of mulch to help retain moisture and keep out competing weeds. Your canna should get an inch of water each week and during dry spells give some water to keep the soil moist. They usually do not need any fertilizer, but a light side dressing of organic fertilizer can be placed around the plant in the spring.
In colder zones after the first frost the rhizome can be carefully dug up. Shake the soil off, trim the roots and then cut the stalk off. The rhizomes can then be stored in a cardboard box with some peat moss or perlite. Store them over the winter in a cool area that does not freeze, such as a basement. Leave the box open to allow air circulation.
In the spring before planting, sort through the canna rhizomes and discard any that are soft. You can divide the rhizomes to enlarge your flower bed or you can give them to a friend. You need to have at least 1-eye bud per division, but you will get better results if each division has 3-eyes. You can do it by cutting the rhizome apart or by twisting it apart. The divisions can now be planted.
Diseases and Pests
Canna plants are relatively free of diseases and pests. Problems with slugs and snails can be avoided by mulching around your plants.
Japanese beetles may occur and can be controlled by hand picking early in the morning. Hold a container of soapy water under the Japanese beetle and then tap the leaf or flower and it will usually drop into the soapy water.
Popular Canna Varieties
Standard varieties: Black Knight, City of Portland, Rosamond Cole, The President, Tropicanna, Yellow King Humbert.
Dwarf varieties: Los Angeles, Lucifer, Pfitzer's Primrose Yellow, Picasso, Pink Futurity, Tropical Rose.
Sources: Eden Brothers, Holland Bulb Farms, Park Seed.
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