Canna indica

Canna indica is a superb tall strain with gorgeous foliage and bright vermilion red blooms. Growing to around 150cm (5ft) tall, the wide banana-like leaves add a tropical feel to the garden. The imposing spikes of gladiolus-like flowers sometimes with gold spots or flames in the petals have four large outer petals and a smaller inner petal making the flower around 12 to 15cm (4 or 5in) wide.

Like all Cannas they do best in a rich moist to wet soil, but this variety can also flower in shade, which makes it easier to keep moist. They are ideal to plant at the back of a border where they are in full sun, or to add colour to a partly shady area. They can also be grown in poorly drained areas and in shallow ponds.
Given an early sowing in spring, they will start flowering from June and are quickly clump forming, making 8 or 10 flowering shoots by the end of the first season.

Cannas can’t help but be focal points: a single specimen can anchor a circle bed. Great for every garden and a perfect choice for the exotic garden, the bright blooms begin in midsummer and continue until frost, for year after year of enjoyment.

Pre-Treatment:
Canna have a very hard seed – hence their common name of Indian Shot. The key to success is to chip or nick the seed-coat to expose the creamy-white inner and to allow water penetration. Without this the seeds may not germinate at all. Use a nail file, sharp craft knife, or a file, (watch out for your fingers!)
Chipped seeds should then be soaked overnight in tepid water until they swell to around 50% bigger than the dry size.

Sowing: Sow January to March for summer flowering, or sow in November for May flowering.
It is best to put each seed in its own pot because the new roots are very fragile and prone to tangling. if you have access to a propagator or heated greenhouse. If you are growing in a warm room, don't sow too early, unless you can provide heat and light to keep the young plants growing nicely through till May, when you will be able to plant outside.
Seeds can be sown four to a 10cm (4in) pot using normal peat-based compost. Sow 12mm (½in) deep and water well. A temperature of 24 to 27°C (75 to 80°F) is needed for germination. Germination takes 10 to 20 days and if the temperature is maintained and adequate bright light provided, growth of the young plants can be rapid.

As soon as the plants are about 15cm (6in) high and there is good root-growth, the plants can be potted on into 15cm (6in) pots using compost with a little added well-rotted manure or slow-release fertiliser granules.
Cannas are very greedy plants and respond well to heavy feeding during the growth period. Fertilise with granular fertiliser and/or with a hose-end sprayer with water soluble fertiliser after plants start to grow and every two weeks thereafter. Put the pots outside after danger of frost (usually first week of May) to allow plants to adjust to the outdoors.

Cultivation:
Cannas are easy to grow but the bed must be well fertilised as the plant is a voracious feeder and a strong grower, and all flowering plants respond well to a good soil environment.
The beds must be dug to a good depth, up to 30cm (12in) at least, and mixed with an appreciable amount of well-rotted organic manure or compost. If possible, make raised beds up to 12cm (5in) high.
Anytime after mid-May, plant in full sun in a rich soil with good drainage. Because of its large leaves Canna dislikes windy conditions since this can tear the leaves to shreds, so find a sheltered place for your plants in the garden. For best growing conditions it requires a deep rich well-drained soil and a sunny position.
Space at least 30cm (12in) apart, this is considered the optimum distance although they can be planted up to 24in (60cm) apart depending on the effect desired. Any closer would mean your plants are fighting for survival at the expense of flowering. In a few months, a single plant would have multiplied to a small clump.

Though drought tolerant, Canna do thrive when well-watered. For best results, Canna should be soaked every day during the hot days of July and August. Weed, manure and water the soil regularly. Mulching around the base of plants and beds is a good practice; this will keep weed growth in check and conserve soil moisture so that the roots are kept cool.
Each plant will produce several shoots of flowers, one after the next. After a flower shoot has died, cut the shoot towards the stalk for appearance and to promote growth of new shoots. All spent flowering stems must be cut right to the soil level. Only then will the new vigorous suckers have the chance for vigorous growth. Dress the Canna beds regularly with organic compost or well rotted manure once every six to eight weeks.

Over wintering:
Canna is not a hardy plant, although it can survive temperatures down to about minus 5°C (23°F) over winter, it needs a good mulch if left in the ground in mild areas. In frost-prone areas the tubers must be over-wintered in a cool but frost-free place, in a conservatory or greenhouse, covered in moist soil or leaves. Harvest the tubers in late autumn, after the top growth has been killed back by frost and store them over the winter.
As Cannas begin to die back at the end of the season, potted plants can be brought indoors. Cut the tops off outdoor plants and lift and clean the corms. They should be stored dry in darkness (the same as with Dahlias) at 10°C (50°F) until the following spring. In March, take the clumps from each box, remove remaining soil, and break or cut the rhizome into sections, each containing at least 3 eyes (prominent red buds). Single-eye divisions may survive but will take longer to produce a vigorous new plant. Each clump will yield four or more new rhizomes. The tubers should be planted 12cm (5in) deep and 30 to 45 (12 to 18in) apart
Canna beds should be replanted every year. Cut off the old roots from the dug-up rhizomes. Trim off the dead roots, retaining only the strong vigorous portions with an upright stem. When you replant or open the old Canna beds the beds may need to be lined with dolomite or magnesium lime to counteract the acidity built-up in the soil through the constant use of organic matter or compost.

Plant Uses:
City/Courtyard Gardens, Flowers Borders and Beds, or Sub-tropical.

Origin:
Canna indica is native to tropical America, but its exact native range is obscure. It is considered to be native to Mexico, Central America, the Caribbean and tropical South America.
Without exception, all Canna species that have been introduced into Europe can be traced back to the Americas. If Asia and Africa provided some of the early introductions, they were only varieties resulting from C. indica and C. glauca cultivars that have been grown for a long time in India and Africa, with both species imported from Central and South America.

Nomenclature:
The genus name canna comes from the Greek kanna and the Celtic cana which refers to 'a reed-like plant' and is also the root of the musical term 'canon'. The name canna was applied to this genus as early as 1576 and was formally given to the genus by Linnaeus in his seminal work Species Plantarum.
Canna is famously called Indian Shot. The story is that during an uprising in India, those loyal to the British were running out of ammunition. So they filled the barrels of their rifles with canna seed. The rock hard, perfectly round seed was used as a substitute for lead shot in muzzle loading guns. Hence the name Indian Shot.
The thick seed coat allows Canna seed to survive for a very long time. In 1969, Canna indica seed was found in a 550-year-old archaeological dig in Argentina and was successfully germinated. The reason that the seed coat may be so thick is that fire plays a part in Canna seed germination in its native habitat. In the wild, canna seed germinates best in places burned by fire, which not only weakens the seed coat, but destroys any competition for the emerging Canna seedling.

Canna is the only genus in the family Cannaceae. Canna (or Canna lily, although not a true lily) is a genus of nineteen species of flowering plants. The closest living relations to cannas are the other plant families of the order Zingiberales, that is the gingers, bananas, marantas, heliconias, strelitzias, etc.
The first Cannas introduced to Europe were C. indica L., which was imported from the East Indies, though the species originated from the Americas. Charles de l'Ecluse, who first described and sketched C. indica indicates this origin, and states that it was given the name of indica, not because the plant is from India, in Asia, but because this species was originally transported from America: "Quia ex America primum delata sit". At that time, one described the tropical areas of that part of the globe as the Western Indies.

Disease:
Canna are remarkably free of disease, compared to many genera. However, they may fall victim to canna rust, a fungus resulting in orange spots on the plant's leaves, caused by over moist soil. Cannas are also susceptible to certain plant viruses, some of which are Canna specific viruses, which may result in spotted or streaked leaves, in a mild form, but can finally result in stunted growth and twisted and distorted blooms and foliage.
Collect seeds from flowers each year and, should your plants fall victim to the disease, burn infected plants at the end of the season.