Edible Canna (Canna indica var. edulis, syn Canna edulis) AKA the Queensland Arrowroot this plant is closely related to the garden canna. It grows 6 or more feet tall and has a small brilliant red flower so it is an excellent backdrop for smaller flowers and herbs.
Soil: It loves wet soil and can grow in boggy conditions but it also thrives in drier soils. Fertilize lightly if at all.
Water: It grows faster and taller in dry conditions when irrigated.
Cold: The stems freeze to the ground in cold snaps but the plant comes back every spring.
Pruning: Dead leaves can be removed for aesthetic reasons, especially the frozen parts in the spring.
Propagation: Seeds sometimes germinate if freshly planted, but usually require scarification. You can also divide clumps.
Pests: A caterpillar is known to eat cannas, and can affect the unrolling of their new leaves. It can be dealt with by hand-pulling or a BT pesticide.
Other problems: The tubers can be fibrous.
Harvesting, storage, and preparation: The flowers, tubers, and stems are all edible.
Historically grown in the Andes as an edible starch the huge tuber was usually roasted for hours until it became soft and sweet. We have not seen this particular variety produce a huge tuber when grown in Florida. The tubers grown here are about the size of regular garden cannas. They are best used to produce a highly digestible thickening powder similar to cornstarch. Shred the tubers coarsely, cover with water and stir. Strain out the fiber with cheesecloth and let the cloudy water settle out leaving the starch on the bottom of the container. Pour of the water and let the starchy residue dry. This makes a fine arrowroot powder.
The bottoms of the stems, up to about a foot, get thick and can be peeled and added to stir fried dishes. They have a bitter-sweet flavor and are quite tasty as a bamboo shoot replacement.
The flowers are ornamental and attractive in salads.
The leaves may be used like banana leaves to wrap food for outdoor roasting or grilling. They will impart a flavor to the cooked food though the leaves themselves are typically not eaten.
More photos on Flickr: https://www.flickr.com/search?sort=relevance&text=Canna%20indica