Thanks to their large, strapping, banana-tree-like leaves and stunning, brightly coloured flowers on tall, sturdy stems, cannas add bold drama to Canadian gardens.
Canna blooms, which are irresistible to butterflies and hummingbirds, come in variations of cream, yellow, pink, orange, salmon or red and can be striped, streaked or spotted. They are low-maintenance plants that will grow and multiply quickly and flower continuously from midsummer until fall.
Though cannas may be grown from seed, they are more often propagated from rhizomes (thick, elongated underground stems). In milder areas, where temperatures never go below freezing, cannas can be left in the ground year-round. For most of Canada, however, they should be treated as annuals or tender perennials that must be overwintered until March, at which time plantings should be started indoors (see "In from the Cold" below).
Native to southern Asia and tropical areas of Central America, cannas are the only genus in the Cannaceae family. Their name comes from the Greek word kanna, which means “reed-like plant.” Often called canna lilies, they are actually not related to the lily family, but are so-named because of their large, exotic-looking flowers.
There are more than 50 species and over 100 canna hybrids available today. Varieties are usually categorized by height as short (under 90 centimetres tall), medium (90 to 180 centimetres) or tall (more than 180 centimetres).
In from the cold
Overwintering should begin after the first autumn frost has blackened the foliage or the foliage begins to wither. Cut stems back to 10 to 15 centimetres. Gently dig up each clump of roots, turn them over and allow them to dry for a few hours. Don't wash. Soil left on the rhizomes will help to keep them from drying out.
Store clumps in barely moist, sterile sand, peat moss, or vermiculite in a cool, dark location. Ideally, place them on shelves or racks, or hang them in mesh bags so that air can circulate around the rhizomes. Don't let the planting mix freeze or dry out during storage. The medium should remain moist but not wet, or the rhizomes will rot.