Species: Cannas

Cannas are currently undergoing a new wave of popularity now that warm colours and bold foliage are back in vogue.  They are approaching their Victorian era popularity. Modern breeders have been releasing some wonderful cultivars and today there are more than 2000 cultivars to choose from.

The genus is native to semi-tropical and tropical parts of North and South America. Their native range extends from North Carolina south to Argentina and includes the Caribbean islands.

Although used for thousands of years as a food crop, Cannas were not well-known to European botanists until the 1500s. By 1576 Cannas were cultivated in gardens in several European countries. However, they only became widely popular as ornamental plants in the Victorian era (mid to late 1800's). Hundreds of cultivars were created between the 1860's and the 1910's with shorter habits and novel flower forms and colours. Unfortunately, most of these cultivars were lost because European gardeners stopped growing Canna during the upheaval from World War I through World War II. Afterwards they were subject to the fickle spells of “Fashion” and only now are they coming back into vogue.

Two modern common names for Canna are 'Arrowroot' (for its high quality starch) and 'Indian Shot' referring to the very hard, pea-like seeds of that have been used as shotgun pellets in India.

Canna varieties grow to between a height of 75-150cm (18" - 5'), but a few like Canna iridiflora may reach 3m (10') or more. The large, banana-like foliage may be green, bronze-burgundy, or variegated in a striped or marbled pattern. If you want a bright, happy, bold garden but you don't live in the tropics, think about planting cannas.

Cannas can be grown anywhere in South Africa.  However in areas where heavy frost occurs, the rhizomes (with between 4 and 7 eyes) should be lifted and stored in dry sawdust at a temperature no higher than 10°C (50°F) or mulched very well in situ until all danger of frost is past.  Most cannas like a sunny position. Off-white flowering varieties prefer dappled shade. They grow well in moist soil enriched with organic matter. Fertilise in late winter with a general fertiliser. Cannas respond well to applications of well-rotted cow manure or compost. Remove spent flower heads to maintain an attractive display. Water AT LEAST once a week. At the end of the flowering season, cut old stems down to within 2cm (1") of the ground. Lift and divide the clumps every two years.

Cannas are valuable as a food source because their rhizomes contain a high quality starch. Canna starch has the largest starch granule size in the plant kingdom and is valuable as an industrial starch in processed foods because it has a low viscosity and does not break down during cooking and freezing.