CANNAS
(Cannaceae)
For sheer exuberance in the garden there are few plants to match cannas. They are big, brash and bold and certainly not for the faint-hearted. Their large leaves come in a variety of colours from plain green or coppery-bronze, through to the dazzlingly variegated varieties such as Canna 'Striata' with cream and green stripes, Canna 'Durban' with rich red, copper, pink and purple hues and the brilliant markings of Canna 'Stuttgart' with broad bands of cream and green. But the fireworks don't end there - from midsummer until the first hard frosts cannas display a profusion of flower colour and form: pinks, reds, yellows, whites and oranges and flower blooms resembling flouncy and wavy gladiolus to petite, tubular, almost fuchsia-like blossoms.
CULTIVATION
Cannas originate from tropical and sub-tropical regions of South America and are tender perennials. With the exception of C. 'Stuttgart' all require a position in full sun or at least very light, dappled shade. Because they are such robust growers the soil should be rich and moisture retentive but free draining. Cannas grown in the open ground make much more growth than those grown in pots. Having said that, they do make good container specimens if potted on regularly culminating in 15-20 ltr pots and fed weekly.
OVERWINTERING
The first severe frost will blacken the leaves and this is the time to dig cannas up and store them overwinter in frost free conditions, cutting the foliage back to ground level and treating the cut parts with yellow sulphur to prevent rot. The large rhizomes can be packed in barely moist sand or compost (we pack ours in bin liners with the tops left open for air circulation). Those grown in pots should be cut down to the base and moved to frost-free conditions. If you have a conservatory or greenhouse heated to above 10 degrees centigrade, cannas will continue to grow throughout the winter months but at a far slower rate.
POT CULTURE
Rhizomes can be divided in March or April and put in containers just large enough to hold them. As new growth appears water sparingly and increase watering as growth develops. Be prepared to pot on as roots fill the pot. When all danger of frost has passed young cannas can be placed in the open ground.
