Red canna root is an edible underground rhizome--a type of root--of the plant known as red canna or achir. The root, easy to cultivate in its native tropical climates, is pealed and boiled to yield a sweet-tasting, starchy and nutritious paste. Allowing the leaves to grow increases the size and number of roots. The plant grows 3 to 6 feet tall at maturity.
Red canna has several synonymous botanical names, and older names may persist in print publications. The American Horticultural Society's "A-Z Encyclopedia of Garden Plants" lists the preferred botanical name as Canna indica, but notes Canna edulis is a valid former synonym. The U.N.'s Food and Agriculture Organization lists Canna achiras as another synonym. Many common names exist for red canna, including "arrowroot," "edible canna," "tous-les-mois," "Indian shot," "balisier rouge" and "toolima." There are many vernacular names for this plant that is now commonly grown as a staple food in impoverished tropical regions worldwide.
Red canna root is native to the Andes Mountains in northern South America and was cultivated by the Incas, according to Tradewinds Fruit Company. The Food and Agriculture Organization mentions it grows like an annual weed across the world's tropics today from sea level to elevations of 9,500 feet in seasonally warm areas.
The red canna root is planted when there is no danger of frost in a sunny location. As early as 180 days later, the plant is dug up and the roots are cleaned and then skinned. The white flesh is boiled to create a slimy, smooth slurry that is eaten as a source of carbohydrates. The root can also be dried and pulverized into an edible flour. If not grown as a food crop, the seeds of the plant are harvested and used as beads for necklaces and rosaries. Gardeners enjoy the green, sometimes reddish green leaves and colorful flowers in the landscape, especially in muddy soils.
Plant red canna root in a fertile soil where it will receive a minimum of 6 hours of direct sun rays daily. It appreciates a continually moist to wet soil; irrigate it during periods of drought. Dry soil can cause the plant to go dormant, only to return when moisture and heat are present. Plants are killed back to the ground by frosts, but rhizomes overwinter underground unharmed in U.S. Department of Agriculture hardiness zones 8 and warmer. Elsewhere, plant roots in spring and dig them up for eating or storage after the first fall frost.
In frost-free regions, red canna may be regarded as a weed since it produces plenty of seeds that are scattered about the landscape and then germinate. Occasionally problems with snails, slugs or caterpillars eating leaves may occur, and spider mites can dry out foliage on plants that are stressed from drought, heat and lack of air flow. Viruses can infect plants and are not treatable, noted by symptoms of random yellow/white flecking or streaking in the otherwise healthy looking leaves. Flecks may also be seen in the flower petals.