Green County MGA

Green County Master Gardeners Association, Wisconsin

Cannas- A Touch of Tropical

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Cannas can add a touch of tropical to any garden with wide, green or variegated leaves and bright flowers in multiple shades of red, pink, orange and yellow. Canna is the only genus in the family of Cannaceae which can be propagated from seed, but most often are grown from rhizomes.  While those in southern climates can keep these lily-like flowers in the ground year around, here in Wisconsin they must be dug and stored indoors for the winter, otherwise the rhizomes will freeze and rot.

Plant rhizomes in rich, well-drained soil, about 4-5 inches deep, after the first frost in our area. The plants, depending on variety will grow from 3 to 5 feet up to 7 or 8 feet tall. The plant will flower late in the summer on a single flower spike, which if dead-headed, may produce another flower before storing energy for next year’s blooms.  Keep the plant moist to ensure the most and long-lasting flowers. Cannas, given their tropical nature, will appreciate hot, humid weather and can prefer full sun, although can tolerate some shade.

Cannas are relatively free of disease, though slugs and snails may find them tasty! Recently, horticulturists have identified several viruses, such as canna yellow mottle virus and bean yellow mosaic virus that impair growth and flowering. These viruses have no cure, so if your plants display symptoms, dig them up and destroy the foliage and rhizomes. Purchasing rhizomes from a reputable nursery, should prevent any virus related problems for you.

For a list of popular canna varieties representing red, yellow and orange flowers as well as variegated leaves, visit the Iowa State University Extension information page here:

http://www.ipm.iastate.edu/ipm/hortnews/2015/01-16/cannas.html