Canna Plant Profile (Canna Lily)

Canna lily

 danhadd137 / Pixabay / CC By 0

Growing cannas in your garden is an easy way to create instant tropical flair. Cannas are tropical and subtropical flowering plants with large, banana-like leaves. Cannas' popularity and active hybridizing have resulted in a dazzling array of cannas to choose from, many with large, showy flowers and variegated leaves that look like stained glass when the sun shines through them.

Striking flowers notwithstanding, cannas are often grown for their foliage alone. The large, paddle-like leaves come in a range of greens and blue-greens and can have variegation and stripes. Somewhat tubular and lily-like, Canna flowers come in shades and combinations of yellow, orange, red, and pink and are borne on tall stalks poking out of the foliage.

Because most Cannas sold today are the result of many crosses, Cannas are rarely classified and are simply considered hybrids.

Botanical Name Canna × generalis
Common Name Canna lily
Plant Type Annual flower (in most zones)
Mature Size 2 to 10 feet tall and 1.5 to 6 feet wide
Sun Exposure Full sun
Soil Type Rich, moist
Soil pH 6.0 to 6.5
Bloom Time Summer
Flower Color Yellow, orange, red, pink
Hardiness Zones 8 to 11
Native Area Tropics

How to Grow Canna Plants

In planting zones 8 and up, cannas will repeat-bloom throughout summer, and throughout the year in zones 9 and above. For everyone else, there are three options: You can let them die off each fall and start with fresh rhizomes in the spring; you can pot the plants and bring them indoors to live as houseplants; or you can dig up and store the rhizomes for the winter (and replant them in spring).

Cannas are not often bothered by insects or disease. Their leaves are covered with a waxy substance that repels water and protects against fungus. Pest problems are minimal, but grasshoppers and caterpillars may munch on the leaves.

Light

Cannas do best in full sun. This means they may need more water in really hot climates, but they need heat to spur their growth.

Soil

Plant cannas in rich, moist soil, ideally with a slightly acid to neutral soil pH.

Water

Cannas need lots of water and are plants that actually prefer "wet feet" (most garden plants don't). You can even grow them in sitting water. Insufficient water will cause the leaves to tear or crack.

Temperature and Humidity

Blooming depends on the climate and weather. In areas with cool springs, the plants may be slow to get started. Potting them up indoors, before your last frost date, and moving them out while they are already growing, will help them bloom earlier. As tropical plants, cannas prefer humid air but can tolerate relative dryness, especially if they are properly watered.

Fertilizer

In addition to needing lots of water, cannas are hungry plants, although they store some food in their rhizomes. Feed them in early spring and midsummer, using a balanced fertilizer.

Propagating Canna Plants

Since most of the newer varieties are hybrids, canna lilies are generally grown from rhizomes rather than seed. If you live in a climate with frost and would like to preserve outdoor plants for the next season, allow the foliage to be killed by a frost. Then, dig the plants and let them dry in a protected, shady spot. When dry, shake off the excess soil, wrap the rhizomes in newspaper, and store them in a dark, cool location until spring. Check on them periodically to make sure they are not rotting or drying out.

In spring (after the last frost), plant the rhizomes 4 to 5 inches deep. Or, if you'd like to get a head start on the season, pot them up indoors, four to six weeks before your last frost, and move them out once the temperature warms. Keep the rhizomes moist but not soaking wet. Once the plants are up and growing, they can handle wet soil.

Varieties of Cannas

  • 'Lucifer': red flowers with yellow borders; green leaves; 2 feet tall
  • 'The President': scarlet blossoms; green leaves; 3 to 3.5 feet tall
  • 'Pretoria' ('Bengal Tiger'): orange flowers; yellow and green striped foliage; 4 to 6 feet tall
  • 'Stuttgart': orange flowers; green and white variegated foliage; 3 to 4 feet tall
  • 'Tropicanna': dark variegated leaves with large, orange flowers; also comes in Black and Gold; 4 to 6 feet tall
Canna lucifer
Canna lucifer.  AlecOwenEvans / Getty Images
Canna president
Canna president. PeterEtchells / Getty Images 
Canna pretoria
Canna pretoria. Andrew Toskin / Flickr / CC By 2.0
Canna tropicanna
Canna tropicanna.  Billy_Fam / Getty Images

Pruning

To keep your plants flowering throughout the season, deadhead them as the blooms start to fade. If you prefer to grow cannas for their foliage alone, you can cut back the flower stalks before they even have a chance to bloom.

Landscape Uses

Cannas can't help but be focal points. A single specimen can anchor a circle garden. Planted in a mass, they can look both tropical and Victorian. The colors and tropical feel combine well with other "hot" colors.

Because they like lots of water, you can even grow cannas in water gardens. Place potted cannas just below water level, and you won't have to worry about hand-watering all summer.