Turn up the heat in summer with tropical cannas. These sizzling sun lovers flower continuously from midsummer until fall, but their foliage provides a spectacular feature long before the blooms unfold. Both leaves and flowers come in many fiery shades reminiscent of carnival costumes from their native Brazil.
Ideal in the center of a display of annual bedding plants, cannas look equally effective in pots on their own, or combined with containers of Crocosmia, Colocasia and bananas to create a leafy, colorful, tropical design. Cannas are frost-tender perennials grown from rhizomes and produce tall stems of magnificent irislike flowers in hot reds, oranges and yellows.
The blooms are often paired with equally flamboyant brightly colored or variegated foliage. Canna ‘Durban’ is one of the best and features a combination of large, luminous orange flowers and dark red foliage with flamelike markings in red, pink and orange. Others are grown for their dark leaves. C. ‘Black Knight,' for example, has sultry burgundy foliage that makes a great foil for its own deep red flowers and other summer blooms.
Given a warm sheltered site where they can bask in full sun, cannas provide a long-lasting display, blooming from mid- to late summer, depending on the variety and continuing to send out new flower shoots until the middle of autumn. However, if you attempt to grow them in even light shade, they are unlikely to bloom. As well as heat, plants enjoy moist conditions and must be watered frequently from spring to fall and never allowed to dry out. They are also extremely hungry, so for robust growth and optimum flower production, feed them every two weeks during the growing season with a balanced liquid feed. Also remove fading blooms, which helps to promote more to form.
Overwintering and Dividing Cannas
To protect your plants over the winter, before the first frost in the fall cut back the leaves and flower stems to 1 inch (3 cm) from the soil surface and move the pot to a frost-free shed or greenhouse. Keep the compost damp, but not overly wet, in the winter and then move plants back outside in late spring or early summer. Spring is also the time to divide rhizomes to make new plants. Clean the rhizomes of compost, then, using a clean sharp knife, cut them into sections, each with a bud, or eye. Pot the rhizome sections in fresh compost.