This group consists of sixty deciduous, rhizomatous, and tropical perennials, which are mostly native to the moist, upland forests of Asia and Latin America. Two, aquatic varieties, C. flaccida and C. glauca, are natives of Southern swamps. These plants are valued for their gorgeous, colorful foliage and attractive, Gladiolus-like flowers. Cannas are commonly known as Indian Shot because of their hard, pea-like seeds. Indian Shot can be grown outdoors in containers or in the garden, as houseplants, or in water, 1 to 6 inches deep if accustomed. From intervals along the branching rhizomes grow large, long-stemmed leaves in a kaleidoscopic of vivid colors. The beautiful flowers grow from the leaves at the tops of the plants. The flowers may be scarlet, apricot, coral, pink, or yellowish-orange, sometimes marked with contrasting speckles. The blossoms are very attractive to hummingbirds. Depending on the variety, these plants may grow from about 18 inches high to over 6 feet. C. indica produces very shiny green leaves from 2 to 6 feet tall and yellowish to orange flowers often speckled with red.
is a tall variety with bronze foliage and brilliant scarlet flowers. 'Robusta' is a purple-leafed cultivar that is among the tallest, growing 9 to 12 feet high on rich soil. 'Pretoria' has bright yellow and yellowish-green, tiger-striped leaves. Another cultivar, 'Wyoming', has such dark plum-colored foliage it almost appears black.
Cannas are hardy from zones 7 to 10. They will survive outdoors in regions where temperatures don't fall below 20º F. In colder areas, lift the rhizomes from the ground in the fall and store them in peat or vermiculite at 41º to 50º F. Grow these plants in any rich, organic, well-drained soil. Well-decayed manure or compost and fertilizer can be added to poor soil. Plant the rhizomes in the spring when soil has warmed, in a sunny location. Place them 3 to 4 inched deep, and depending on the cultivar, 1 to 3 feet apart. Water and fertilize well throughout the growing season. In regions where they can remain outdoors during the winter, cut the tops of the plants to the ground when they freeze. If the winter temperature of your region gets to cold, however, dig up the rhizomes and store as mentioned previously.
If your plants are to grow in water but they haven't before, they must first be adapted to it. This is accomplished by keeping them moist and gradually increasing the water to an inch or so above the plant's crown. They may eventually be covered with 1 to 6 inches of water during the summer. If they are going to be brought in during the winter, plant them in 5-gallon containers before submerging them in the water garden. In the fall, the plants may be brought in and treated as tropical houseplants or the rhizomes may be hosed free of soil, dried and stored in a frost-proof room as done with terrestrial Cannas.
Where Cannas are hardy, they may be divided every three or four years. Cut the rhizome into sections containing two or more growing tips. Seeds may also be sown in warm soil (about 70º F) in the garden or in a container. Because the seeds are so hard, they must first be soaked for 24 to 48 hours.