Wednesday, 7th June 2023

Colourful canna lilies

By Sereba Agiobu-Kemmer
23 July 2016   |   3:23 am
Cannas are among the most colorful, flamboyant perennials. These rhizomatus perennials come in a vast variety of colors and boast immense, often- veined, paddle-shaped leaves and sheathing leaf stalks...

Cannas are among the most colorful, flamboyant perennials. These rhizomatus perennials come in a vast variety of colors and boast immense, often- veined, paddle-shaped leaves and sheathing leaf stalks depending on the variety of foliage color which varies from green to maroon, bronze and variegated types. With their great reedy canes and palmy foliage, cannas would be magnificent plants, even if they never bloomed.

Canna lilies are low-maintenance and easy to grow, both their flowers and foliage offer long-lasting color in the garden. Canna (or canna lily, although not a true lily) is a genius of 10 species of flowering plants. The closest living relations to cannas are the other families of the order Zingiberales, that is the Zingiberaceae (gingers), Musaceae (bananas), Marantaceae, Heliconiaceae, Strelitziaceae etc. Canna is the only genius in the family Cannaceae. The species have large, bold foliage, and horticulturists have turned it into large-flowered and bright garden plants.

Many varieties have multi-colored and patterned leaves making them season long focal points in the garden.

In addition, it is one of the world’s richest starch sources, and is also an agricultural plant. The Canna Agricultural Group contains all of the varieties of canna grown in agriculture. Cannas that have been selectively bred for agricultural purposes, normally derived from Canna discolor (Canna edulis). “Canna achira” is a generic term used in South America. It is grown especially for its edible rootstock from which starch is obtained, but the leaves and young seeds are also edible. Although Canna is a native plant of the tropics, but most cultivars were developed in temperate climates and are easy to grow in most countries of the world, even those with territories above the arctic circle which have short summers but long days; as long as they receive at least 6-8 hours of sunlight, and are moved to a warm location in winter.

The name canna originates from the Latin word for a cane or reed. Canna comes in eye-popping colors of red, orange, or yellow or any combination of these colors and sometimes in demure pastel tones and are aggregated in inflorescences that are spikes or panicles (thyrses). All attract pollinators collecting nectar and pollen, such as bees, butterflies, humming birds, sunbirds and bats.

The pollination mechanism is conspicuously specialized. Pollen is shed on the style while still in the bud, and in the species and early hybrids some is also found on the stigma because of the high position of another, which means they are self-pollinating. Later cultivars have a lower anther and rely on pollination alighting on the labellum and touching first the terminal stigma, and then the pollen.

The wild species (C.indica) often grow to at least 2-3m (6.6-9.8 ft) in height but there is a wide variation in size among cultivated plants; numerous cultivars have been selected for smaller stature that are easy to fit into our down-sized modern gardens.

A large number of ornamental cultivars have been developed, and can be grown in tropical, subtropical outdoors in borders, beds, as patio or deck plants or in containers. When growing cannas in the garden, placing them in mixed borders or group planting will offer the most dramatic effects.

Internationally, cannas are one of the most popular garden plants and a large horticultural industry depends on the plant. Exotic cannas are tropical creatures, so they like plenty of heat, so place them in full sun. They can also tolerate partial shade.

In cooler climates, they are typically grown as annuals, given the proper conditions; canna lilies can color the garden year after year. Canna like fertile moist conditions too, but will tolerate nearly any well-draining soil that is either neutral or slightly acidic soil. They appreciate bog-like conditions as well.

Cannas are used to attract many undesirable pollutants in a wetland environment, as they have a high tolerance to contaminants. Cannas grow from swollen underground stems, correctly known as rhizomes, which store starch, and this is the main attraction of the plant to agriculture, having the largest starch particles of all plant life.

All of the plant has commercial value, rhizomes for starch (consumption by humans and livestock), stems and foliage for animal fodder, young shoots as vegetable (‘achara’ in Ibo language), and young seeds as addition to tortillas.

Dwarf cannas stay under 3 feet tall. The 2 ½ foot tall ‘Picasso’ is a yellow-flowered dwarf peppered with freckles.
Standard varieties grow 4-6 feet tall and need a 20-24 inch circle for each hand-size ‘rhizome’. The ‘President’ is red, ‘Yellow king’ is spotless, ‘Rosamund Cole’ is orange edged gold, and ‘City of Portland’ is salmon pink.

Many gardeners love the spectacular drought-tolerant varieties that reach heights of over 6 feet. Such is the rich, deep pink ‘Los
Angeles’, which has large floret and opens out so you can see the face,

‘Bengal Tiger’ is stunning even when it is not blooming with green-and-yellow-striped maroon-edged leaves and bright orange flowers.

Cannas grow best in full sun with moderate water, in well-drained rich or sandy soil. They grow from perennial rhizomes, but are frequently grown as annual in temperate zones. In arid regions, cannas are often grown in water garden with lower inch of pot submerged. In all areas, high winds tear leaves, so shelter is advised.

How to plant
Prepare the garden bed by using a garden fork or tiller to loosen soil to a depth of 12-15 inches, mix in a 2-4 inches layer of compost. Dig a hole 4-6 inches deep. Set the rhizome horizontally with the eyes facing up. Cover the rhizome with 3-6 inches of soil, press firmly.

Space rhizomes 1 to 4 feet apart, depending on its variety. Water thoroughly. If you grow from seed, note that the germination rate is low and the seed need to be filed or given an acid bath to break down their hard coat. Growing from seed is not easy; better to leave propagation to the experts. Grow from the tubers instead.

Once established cannas need to be kept in consistently moist soil. Keep a thin layer of mulch around canna to help retain moisture and weed control. Water plant during dry season and water container plants frequently to keep moist. Stake tall varieties if needed.

As flowers fade, deadhead to promote continued flowering. Cut each stem to the ground after bloom. They also require monthly fertilizer that is relatively high in phosphate for continued bloom. Every 3 to 4 years dig up clumps when they have grown very matted, separate the roots, and plant them in well- enriched soil.

Cannas are remarkably free of diseases, compared to many genera. However, they may fall victim to canna rust, a fungus resulting in orange spots on plant’s leaves, caused by over moist soil.

They are also vulnerable to certain plant viruses, some of which are canna-specific, which may result in spotted or streaked leaves in a mild form, but can result in stunted growth and twisted and distorted blooms and foliage.

The flowers are sometimes affected by a grey, fuzzy mold called botrytis. Under humid conditions, it is often found growing on older flowers. Treatment is to simply remove the old flowers, so the mold does not spread to the new flowers. Slugs (snails and caterpillars) may be problems, as they love to feed on the lush foliage.

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