Canna iridiflora EhemanniiTuberous perennials from South America, Canna are perfectly at home in our Sydney gardens. They belong to the plant family Cannaceae, of which they are the only genus, and they have links with other tropical plants such as gingers, banana trees, Strelitzia and Heliconia.
Previously spurned as vulgar, Canna have had a return to popularity in recent years and their attributes are now much appreciated. Flamboyant and showy, they bloom throughout summer and autumn, only fading when the cold weather really begins to set in around May. They give a tropical, exotic touch to our gardens, mingling happily with other summer flowers. The fleshy paddles of the canna leaves are an added bonus.
Modern hybrid cultivars tend to have large, clustered flower heads, but the original species ones have more delicate flowers. This beautiful example has pendant cerise flowers and always looks very graceful. It is tall - 2-3m - and multiplies quite rapidly. The cultivar 'Ehemannii', which was developed in the nineteenth century, is the form of this plant most commonly seen in cultivation, and has a similar flower and an attractive red margin to its leaf. It mixes beautifully with flowers of pinks, blues and purples, such as Salvia, Brillantaisia and Pentas.
Like all Canna, it needs a full sun position and rich, moist (but well-drained) soil. It needs to be dug up and divided every few years in spring and replanted in soil which has been amended with plenty of compost and decayed manure. When dividing them, simply chop up the young, healthy parts of the tuber into pieces with some roots and growing points attached and discard the old gnarled sections. It definitely benefits from being deadheaded regularly during the flowering season, as this will stimulate the production of more blooms. When a stem has completely finished flowering, it can be cut back to the ground to allow a new stem to develop. They love regular applications of fertiliser throughout the warmer months, being greedy feeders. Cut them completely back to the ground around June. Snails and slugs enjoy the fresh shoots in spring, so these need to be watched out for then. If the plants are well fed and watered, there should be few other problems. If leaves get affected by rust, remove them and dispose of them in the rubbish bin rather than the compost heap.