Best grown in moist, organically rich, well-drained soils in full sun. Rhizomes may be left in the ground in USDA Zones 7-10, however in the St. Louis area (Zones 6a-5b), the rhizomes should be lifted in fall for overwintering. Plant rhizomes 4-6” deep and 18-24” apart in spring after threat of frost has passed. Remove entire flowering stems immediately after bloom. In fall, cut plants to the ground after first frost and lift rhizome clumps for winter storage in a dry medium (peat or vermiculite) in a cool dry location than does not fall below 40 degree F. Rhizomes may be occasionally sprayed with water in winter to make sure they do not become so dry that root shriveling would occur. Container grown plants can be stored in their containers in winter. Propagate by division in spring before replanting outdoors.
Cannas are large rhizomatous tropical plants that produce flower spikes in summer atop erect stems sheathed in large paddle-shaped leaves.
Genus name comes from the Greek word kanna meaning a reed.
‘Australia’ is a popular purple-leaved cultivar that grows 4-5’ tall. It features burgundy-black leaves (to 10-20” long) that hold the foliage color well through summer. Bright red flowers (to 3” across) appear in racemes atop burgundy-black stems from mid-summer to fall. Dramatic foliage provides considerable ornamental interest when the plants are not in flower.
Rhizomes may rot in poorly drained wet soils. Leaf spots, rust and bacterial blight may occur. Watch for aster yellows. Japanese beetles, caterpillars, leaf rollers, slugs and snails may chew on the foliage.
Group or mass in beds or borders. Effective planted with both annuals and perennials. Foundations. Large containers. Leaves are particularly impressive when backlit by sun.