The Canna generalis, commonly referred to as the large-flowered canna, is a perennial herb that grows up to 100-150 centimeters tall, with thick rhizomes forming tuberous underground stems.
The large leaves are arranged in a spiral pattern, featuring prominent central veins and pinnate parallel veins. The petioles are sheath-like and clasp the stem without any ligules, appearing circular in cross-section and colored either green or purplish-red.
The stems and leaves are covered with a white powder. The broad, elliptical leaves set the stage for the plant’s sizeable flowers, which can span up to 20 centimeters and display petals that stretch outwards, encompassing four petal-like stamens.
The blossoms come in shades of cream, yellow, orange-red, pink, scarlet, to purple-red. Known as a collective term for French cannas, the large-flowered canna mainly results from hybridizing and improving the original species native to the tropical Americas.
With their rich green foliage and vibrant blossoms in tones ranging from cream, pale yellow, orange-red, pink, scarlet, to purple-red, and even some speckled with gold, they are ideal for creating a dramatic backdrop in flower beds or as a centerpiece in garden arrangements.
They can also be planted in clusters or belts along the edges of forests or meadows.
The large-flowered canna stands at about 1.5 meters tall and both the stems, leaves, and inflorescences are dusted with a white powder.
The elliptical leaves can reach up to 40 centimeters in length and 20 centimeters in width, with purple leaf margins and sheaths.
The terminal raceme inflorescences are 15-30 centimeters long (including the main flower stalk); the large flowers are rather dense, with 1-2 blossoms per bract.
The sepals are lanceolate, measuring 1.5-3 centimeters long; the corolla tube is 5-10 millimeters long, with lanceolate corolla lobes spanning 4.5-6.5 centimeters in length.
The three outer whorls of staminodes are obovate-spatulate, 5-10 centimeters long and 2-5 centimeters wide, with a variety of colors including red, orange-red, pale yellow, and white.
The lip petal is also obovate-spatulate, about 4.5 centimeters long and 1.2-4 centimeters wide; the fertile stamen is lanceolate, about 4 centimeters long and 2.5 centimeters wide; the ovary is spherical, with a diameter of 4-8 millimeters; and the style is ribbon-shaped, with the free part measuring 3.5 centimeters long. The blooming season is in the fall.
The large-flowered canna is a general term for French cannas, primarily developed through the hybridization and improvement of the original species found in the tropical regions of the Americas. It is widely cultivated throughout China.
This species thrives in a warm, moist climate and does not tolerate frost. It prefers temperatures between 25-30°C and flourishes in full sunlight and fertile soil.
In its native habitat, it grows and flowers year-round without a dormant period. The plant is robust and adaptable, nearly indifferent to soil types, though it favors moist, fertile, and loose sandy loam.
It can withstand slight waterlogging but is susceptible to strong winds. Planting occurs after the last frost in April or May.
As the stems sprout, flower buds form, and blossoms open from the bottom up throughout the growing season, ensuring continuous blooming from June until the first frost. The total flowering period is extensive.
In regions south of the Yangtze River, the rhizomes can overwinter in the ground, but north of the Yangtze, artificial protection is needed for overwintering.
The plant is sensitive to cold, strong winds, and frost. It is not overly particular about soil and can tolerate poor conditions, though it grows best in fertile, moist, and well-drained soil.
After the plants wither in late autumn, the above-ground parts should be pruned, the rhizomes dug up and dried for 2-3 days, then buried in well-ventilated sandy soil in a greenhouse.
Without watering, maintaining temperatures above 5°C will ensure they safely overwinter.
From April to May, nick the hard seed coats with a sharp object and soak in warm water for a full day and night before direct seeding outdoors.
Seedlings emerge in 2-3 weeks, and once they have developed 2-3 leaves, they should be transplanted. Flowers will bloom in the current or following year.
Tuber propagation should be carried out between March and April. Dig out the old rhizomes and divide them into sections, ensuring each piece has 2-3 buds and roots attached.
Plant them about 4 inches deep in the soil, spacing them 16-20 inches apart, and water thoroughly. Once the shoots have 5-6 leaves, fertilize with mature compost for flowering within the current year.
The canna lily commonly suffers from diseases such as viral variegation, rust, black spot, and fusarium wilt.
Viral Variegation: Mainly caused by the cucumber mosaic virus, which spreads through sap contact and aphids.
Since cannas are often propagated through division, the virus can be transmitted year after year, worsening over time. The virus has a wide range of hosts and can infect many plant species.
Control: Infected plants must be removed and destroyed promptly. Do not use diseased roots or stems for propagation. Throughout the growing period, control aphids to prevent disease.
Rust: In the early stages of infection, yellow water-soaked circular spots appear on both sides of the leaf, particularly on the underside.
These spots rapidly enlarge, causing the leaves to curl and wither. Wind and splashing water can spread the uredospores to healthy leaves, where they germinate and invade, causing repeated damage.
The incidence of the disease is still severe in cool weather, while hot, dry weather tends to alleviate it. Symptoms are usually seen from March to April.
Control: During winter, remove and burn diseased leaves and plant debris. Spray with a 65% zinc dimethoate solution at a rate of 400 times dilution once a week for 3 to 4 times, or apply a 0.3 degree lime sulfur mixture once, or a 20% diniconazole emulsion diluted 2000 to 3000 times. Alternate the use of these treatments to alleviate the disease.
Black Spot: The fungus causes yellow spots that enlarge into circular or oval shapes, 5-15 mm in diameter, and turn brown to dark brown.
The fungus overwinters on fallen leaves, causing damage from May to June, with the most severe outbreaks occurring in July and August.
Control: Strengthen management and avoid planting too densely. When the disease occurs, spray regularly with a 50% tolclofos-methyl solution diluted 500 to 800 times or a 65% zinc dimethoate solution diluted 500 times.
Fusarium Wilt: This disease mainly affects the leaves, showing reddish-brown fusiform or blackish-brown oval spots. In humid and shady weather, a thin grey mold layer appears on the underside of the spots.
The fusarium that causes this disease overwinters on the plant debris and spreads through the wind the following spring under suitable conditions, infecting plants.
Control: In autumn and winter, thoroughly remove and destroy the infected plant debris to reduce the overwintering fungus and control the disease next spring.
Chemical Control: In areas with severe disease, remove diseased leaves and spray with a 50% carbendazim wettable powder diluted 600 times, or a 70% methyl tolclofos-methyl wettable powder diluted 800 times, or a metalaxyl powder diluted 500 times.
Canna lilies have few pests, but some common ones include the leaf roller and cutworms.
Leaf Roller: The larvae roll the leaves to feed on them. In heavy infestations, the leaves become curled and damaged.
Control: Remove the rolled leaves and kill the larvae inside. Clear away dead leaves and plant debris in winter and spring to eliminate overwintering larvae. Spray with a 90% dichlorvos solution diluted 800 times to kill the larvae.
Cutworms: Neat rows of holes can be seen on the plant leaves, and severe infestations can damage flower buds, leading to flowerless plants.
Control: Spray with a mixture of dichlorvos, dimethoate, and esfenvalerate.
The lush leaves of the Canna Lily boast brilliant blooms in shades of cream, pale yellow, orange, pink, deep red, purple-red, and speckled gold.
These plants are ideal for creating a stunning backdrop in floral borders or as a centerpiece in flower beds.
They can also be planted in clusters or strips along forest edges or grassland perimeters. Dwarf varieties are suitable for container planting or as ground cover on sunny slopes.
Canna Lilies are widely used in landscaping for road greening, residential area beautification, industrial sites, and parks, offering significant visual impact and rapid growth.
Canna Lilies not only beautify our surroundings but are also capable of absorbing harmful substances such as sulfur dioxide, hydrogen chloride, and carbon dioxide.
They have a good level of resistance; although their leaves are easily damaged, new growth quickly emerges, restoring the plant’s vitality. Their sensitive response to damage has earned them the nickname “living monitors” of harmful gas pollution in the environment.
They play a role in air purification and environmental protection, making them ideal plants for greening, beautifying, and purifying our surroundings.
The flower language of the Canna Lily speaks of a ‘robust future.
According to Buddhist tradition, the Canna Lily originated from the blood that flowed from the toes of the Buddha himself, forming this grand bloom. When it flourishes in the intense heat and sunlight, it conveys a powerful will to exist.
Peggie was once a high school mathematics teacher, but she set aside her chalkboard and textbooks to follow her lifelong passion for flowers. After years of dedication and learning, she not only established a thriving flower shop but also founded this blog, “Flowers Library”. If you have any questions or wish to learn more about flowers, feel free to contact Peggie.
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