The flowers are solid or combined reds, yellows, oranges and shades thereof.All of the plant has commercial value: (1) Starch for human & livestock consumption. It is one of the world's richest starch sources & is considered an agricultural plant. (2) Stems and foliage for animal fodder. (3) Young shoots as a vegetable. (4) Seeds in tortillas, for beads in jewelry, as hota seeds in musical instruments & for purple die. And (5) Stem fiber is used for making paper and as a jute substitute.
In nature, they exist to attract pollinators such as bees, hummingbirds and bats. These pollinators collect nectar and pollen.
Cannas grow best in full sun with moderate water in well-drained (too much water & they rot) rich or sandy soil. I've found they prosper when fertilized with fish emulsion. Both commercial or dipped out of your fish tank works.
The rhizomes are frost tender and will rot if left unprotected in freezing conditions. Although I've had them come up years later from times when I didn't lift and store.
Cannas are typically not killed by either disease or pests but there is something going around among canna breeders that cautions you not buy unless you know your source is reputable. Old House Gardens recently stopped selling cannas because they were having this trouble.
Cannas are blooming right now and they are a riot of color. They are valued in the north for their color when most other plants have stopped blooming. The leaves are huge. They are often called foundation plants but look equally beautiful placed here and there in a bed, used in groups for formal design or large impact and around ponds. The flowers can be picked for vase or to float. They are also used as houseplants.
This fall, wait until the foliage dies and lays on the ground (they take on nourishment for next year's flowers). Dig rhizomes right after the first frost, trim off any dead leaf material, gently brush off extra soil, lay them single deep and dry for several days (perhaps on a newspaper in the garage.)
Storage is a dice throw. I put them in large paper grocery bags & hang from the basement rafters. I've stored in large plastic garbage tubs but they may rot. If your basement or other storage place is damp, run a dehumidifier. The temperature should not be below freezing nor be above 45 degrees. Rot is the biggest threat although mice may eat.
All canna photos are from http://www.americanmeadows.com/ Beautiful photos but I've never purchased from them and can't say anything about this site other than they have many "wow value" cannas. I bought this year's cannas at the Salvation Army Thrift Store in Galesburg - 12 for $2. They are old fashioned red cannas and I'm enjoying them immensely. I canna and I did.