Cannas are very important and popular perennial flowering plants and grow abundantly in the humid tropical regions throughout the world. They are very hardy and thus grown easily and successfully. The flowers have many shades of colour, appear throughout the year and make a wonderful display of colour which can hardly be surpassed by any other perennial plant. Cannas are frequently grown in private gardens but more extensively in the public gardens. As the flowers do not last long as cut flowers and are very common garden plants, visitors do not show much interest to pluck the flowers or pamage the plants. Cannas alone with their various shades of colour can make a garden quiet attractive.
The genus Canna has about 50 species, native of Tropical America and Asia. The following three species of Canna are considered to be the parents of the present cultivated varieties.
Rhizome stout, stem slender green 1 to 1.2 m high. Leaves oblong 45-60 cm long green, flower in simple raceme or in pairs; sepals-short, waxy; petals-pale pink, lanceolate; staminodes 3 red or rose about 5 cm long.
Stem rather slender, 1.2 to 2 m high. Leaves ovate-lanceolate 20-30 cm long. Flowers few flowered raceme, pale yellow to sulphur; sepals-small; petals-linear-lanceolate, up to 7 cm long; staminodes-3 about 7 cm long.
Stem green 1 to 1.2 meters high. Leaves oblong or broadlanceolate, 25-40 cm long. Flowers on simple raceme pale yellow; sepals-oblong green white margined; petals-lanceolate pale yellowish white; staminodes pale yellow.
In India improvement of canna has chiefly been achieved through hybridisation. A large number of varieties have been developed as a result of hybridisation and selection and these varieties are now commonly grown in the gardens. Depending on the size and shape of the flowers, cannas have been classified as follows:
The selections are the results of 45 years of hybridisation and are a great improvement on the crozy types from which they are derived. The size of the flowers markedly increased with a wide range of colour.
In this class an ideal variety cupid has flowers on closely branched spikes. The plants of this variety are dwarf.
This is a distinct break. The main flower stalk branches and as many as 8-12 spikes are produced instead or two or three.
These are improved hybrids raised by Anne in about 1850 and Vilmorin in 1880.
A great advance on the ordinary crozy or gladiolous flowered canna both as regards the individual flowers and bunches.
This type include varieties which does not exceed the height of 70-80 cm at any time of the year and are very effective for breeding purpose.
Originated in Italy and was very popular for many years. The large blooms of silky appearance resemble the Flag Iris, but not very hardy.
This is small flowering type derived by crossing a societys dwarf hybrid with Canna indica. The spikes are neat and compact.
Cannas can also be divided into several classes according to the colour of the flowers.
The shades of colour cover a wide range from creamy whit through yellow, orange and pink to an intense maroon red. There is no blue or purple colour in canna. There are also few varieties with dark leaves usually reddish purple, also producing dark red flowers. In one variety, however, the leaves are striped yellow.
Canna is commonly propagated by rhizome. Seeds are used for raising new varieties through hybridisation. The seeds have hard seed coat and take a long time to germinate, if the seeds are not treated with hot water or rubbed on a sandpaper.
New varieties result by hybridization. For this purpose they are raised from seeds. Bud sports also produce new varieties. The seeds are of a small pea size and black in colour with a hard seed coat. The seeds are scarified by filing, or by rubbing with a sandpaper or a small portion cut off with a sharp razor blade without injuring the embryo which is inside the seed. This treatment ensures the better germination of seeds. Sometimes, soaking of seeds into water overnight or keeping them in cowdung before sowing is also useful obtaining better germination.
The rhizomes are collected in the month of May and then planted to get the full benefit of the Monsoon and a strong clump forms before the winter. The soil is prepared by digging at least 50 cm deep, breaking the clods and mixing in fresh stable manure at the rate of 100 kg to a bed of 10 sq. metre. The rhizomes are buried 3 cm below the surface of the soil and thoroughly flooded. If the weather is hot and dry, shade is provided for a few days. Planting is done at a distance of 30-40 cm between the rows and the plant. Within six weeks after planting first flower spikes appear which should be removed to. Encourage better growth. The bed should be kept free from weeds by frequent weeding. After the rain ceases and the soil thoroughly dries, it is loosened and allowed to dry. Digging and watering of the bed are necessary at least once a month in the winter and more frequent flooding is recommended to keep the soil moist. After the first flush of flowering is finished in December, leaf-mould or cowdung manure should be applied to the beds to ensure good flowering in the second flush from April to June.
Canna is replanted every year. The rhizome is lifted with a forked hoe, cleaned properly and the top growth cut leaving a stem of about 15 cm. The clump is then split taking only the strongest: root and stored in a shady place for a week or so before replanting. The canna beds should be kept clean by collecting faded flowers and removing dry leaves.
Cannas can also be grown in 30-35 cm pot and the compost should consist of 2 parts stable manure and 1 part garden soil. The potted plants should be replanted every 6-9 months as the roots become pot bound.
Pests and Diseases
Cannas are hardy plants and are particularly free of diseases. Caterpillars occasionally attack the leaves specially during the rainy seasons and bettles sometime destroy the flowers. Application of insecticides like Malathion, Basudin, etc. will keep away the insects.
Varieties of Cannas and Their Flower Colour: