Cannas: Planting, Growing & Caring for Magnificent Canna Plants
Cannas is a genus of the Cannaceae family, of the Zingiberales order that consists of more than 50 varieties of plants.
Naturally, cannas are common in the Central and Southern America, India and China. In the 16th century the plant was brought to Europe by portuguese marines, but only a hundred of years later european gardeners started cultivating cannas.
In Latin, canna means 'a tube', from Greek it's translated as 'reed', and really stems of these plants look very similar to each other.
An old legend says that first cannas popped up on a place of the fire, where an indian chief burnt a wampum with a treaty of peace, therefore unleashed the war. Red-hot petals of first cannas looked pretty much like tongues of the fire and also reminded of blood that has been shed in the war .
Gardeners see the value of cannas not only in their beautiful flowers, but also in their large decorative foliage. The leaves can have dark green, dark purple, red-bronze or even violet colour.
- Characteristics
- Canna species
- Cultivating cannas outdoors
- Planting and handling of outdoor cannas
- Indoor cannas
- Cannas after flowering
- Storing over winter
Characteristics
At the first sight the flower of canna looks much like a hybrid of banana and orchid (or gladiolus) flowers.
Flower gardeners say that cannas are ideal plants to cultivate, and have only two disadvantages: they are sensible to frost and have absolutely no scent. The biggest plus is that cannas are disease resistant, therefore they are easy to grow and handle even for beginners.
Magnificent cannas have a high decorative value. They bloom from June to the first frosts, are simple to care and stable during hot, dry seasons.
Canna rhizomes branch in breadth. Flower stalks are straight, thick and tall (60 cm to 3 m high). The strong leaves are large, elongated, arrowhead shaped, 25 to 80 cm long and 10 to 30 cm wide.
The plant is interesting even without flowers, thanks to the shape and tone of its leaves. But when it starts blooming you can see what the true beauty and harmony is.
Flowers are clearly asymmetrical, androgynous, about 4 to 8 cm in size. Originally they are red, but today, thanks to the work of flower breeders, there are also species of canna in yellow, pink and orange colour. Some types are bicoloured, others are speckled or have a contrast brim.
Canna Species
Canna indica
It is a progenitor of almost all popular canna species. The cultivars of Canna indica (nowadays known as garden cannas) are the result of many years of plant breeder works. Flower gardeners divide these hybrids into three groups:
Crozy group
Low-growing cultivars (60 to 160 cm) with flowers that are very similar to gladioli. The foliage is dark green or purple-bronze, with a white touch. The very first crozy hybrid has been grown in 1868 by a french breeder Crozy. That's where the hybrid's got its name from, and that's why sometimes you can see it named as a French canna.
Some of the best varieties of Crozy cannas are:
Livadia – up to 1 m high, with 25 to 30 cm long inflorescences, with raspberry-red flowers and purple leaves.
America – 120 to 140 cm high stems with vermilion-red 12 cm in diameter flowers. Inflorescences are about 30 to 35 cm in length, the foliage is purple.
President – up to 1 m high stems with flamboyant red flowers. Inflorescences about 30 cm long, leaves are green.
All these cultivars start flowering around July in the hardiness zone 7 or less, and around late spring in the zones 8 or higher.
Canna orchioides
The flower shape of theses cannas reminds of cattleya flowers. These species are 1 to 2 m high, have big (12,5 to 17,5 cm) flowers with ridged boarders. Leaves are green or violet-green.
The popular types of canna orchioides are:
Andenken an Pfitzer – 110 to 140 cm high stems with 30 cm long inflorescences. Flowers are rich orange with red pattern. Leaves are brown-purple.
Suevia – stems are up to 1 m high, flowers have lemon-yellow petals, inflorescences are about 12 x 15 cm. Leaves are green. Blooms a bit earlier than the other orchioides.
Richard Wallace – up to 1 m high, flowers are light yellow with red dots making a 20 to 23 cm long inflorescence, green foliage.
They also start flowering around July in the hardiness zone 7 or less, and around late spring in the zones 8 or higher.
Foliage group
Less common in nature, foliage cannas can grow up to 3 m in height. They have amazing leaves in green, violet, or mixed colours. Flowers are tiny, mostly no bigger than 6 sm in size. The most known type of this group is Durban. It's got vibrant yellow flowers; leaves are pink, bronze, yellow and green, striped. Foliage canna is a real adornment for your garden!
Cultivating Cannas Outdoors
Sowing
Often, seeds of canna don't keep the varietal differences. Also, not all the species set seeds. Therefore the best way to propagate cannas is by rhizomes division.
For real breeding enthusiasts the propagation of cannas by seed is obviously worth trying. Seeds of canna are notable for their hard cover, that needs to be softened before seeding. Pour boiling water over the seeds, and keep them in a thermos cup for 3 to 4 hours, or on a heater for 12 hours. Another way to soften the seeds is to put them in a freezer for 1 to 2 hours.
Around February start seeding your future cannas into the light soil. The optimal room temperature is 22 to 23 °C. Keep the pots in the half-shade.
After 3 to 4 week there will be first sprouts popping up. When they get 3 to 4 leaves, transplant the seedings into pots per one and keep them at the room temperature around 16 °C. There they need to stay until you plant them into the garden beds outdoors.
Some of your seeding may turn into a blossoming plant the same year already. Others will only start flowering next year.
When you want to be sure that your young cannas start blooming this summer, it's better to choose a root division method for propagating. In the beginning of March divide the rhizomes so that every part has one big bud and a few weak ones. Dust the cut sides with wood coal powder, make sure they are dry.
Put divided rhizomes next to each other on the soil (or sand), horizontally, buds up in a hothouse container. Pour sand on top and once a while spray it with warm water. The ideal temperature for sprouting is 20 to 24 °C. Even better if you warm the container also from the bottom.
When leaves of the first sprouts become too big for growing close together, transplant the seedings into pots and put into the room where the air temperature is 16 °C or lower. To support your sprouts, water them with potassium permanganate solution (2 g for 10 l of water) once in 10 days, or just use a growth enhancer available in the local gardening stores, Nitrozyme® for example.
If the climate where you live is warm enough (zones 8 and higher), you can plant divided rhizomes straight into garden beds, without preparatory sprouting indoors. You can even do it in the zones with colder climate, but most possibly your cannas will have delay in blooming or won't flower at all.
When to Plant Cannas?
When the last frosts are over, start preparing a site for cannas. Canna loves growing in the fertile, rich, warm soil on a site with no drafts and with the full sun. Let's say, the growing conditions for cannas are the same as for cucumbers.
To make the ideal growing medium mix black mold, humus, leaves mould, fine gravel and peat. A good drainage is required!
The best period for planting cannas outdoors is around May, or when you are sure that frosts are over and there will be no big temperature differences anymore. Otherwise, outdoor cannas will delay in growth, blooming and, probably, will not start flowering at all.
Planting and Handling of Outdoor Cannas
Planting During the Spring
So when the weather can't harm your plants anymore, it's the time for planting them into garden beds outdoors. To get the max from your cannas, create a “hot bedding”. Make a planting hole 50 to 60 cm in diameter, put a 20 cm layer of manure that will keep the rhizomes warm, therefore force growing and blooming. On top of the layer of manure put a 25 cm layer of soil, moisten it well and only then put canna rhizomes in the planting hole, cover with ground and press.
When you plant rhizomes that are not yet sprouted, put them in the hole no deeper than 6 to 9 cm. Rhizomes (as well as rows) need to be placed about 50 cm apart.
First blooming is expected 1,5 to 2 months after the planting.
Handling of Outdoor Cannas
Canna needs to get fertilizers two or three times during its vegetation. For 1 m² you will need 40 to 50 g of mineral fertilizers mix: 10 g of potash, 12 g of nitrogen and 25 g of phosphoric manure. After watering, spread the pellets around plants and loosen the soil.
For the rest, handling of cannas is pretty easy. Regularly but moderately water your cannas until they sprout. From the moment when the plants start blooming moisten them thoroughly, but watch out: overwatering can cause fungal or bacterial diseases that blacken or even kill flower buds.
Sometimes, foliage can be harmed by caterpillars, and roots can be damaged by nematodes. You might need to use pesticides to control the pests.
Routinely check if there are wilted flowers and remove them. Especially in the first half-growth control weeds around your cannas.
When the blooming period is over, you need to hill up the plants before the first frost. Make the hills quite high, so you will protect the roots from possible subfreezing.
Indoor Cannas
Growing Cannas Indoors
Cannas are very easy to grow in pots or tubs indoors. Just choose those species that fit into the room or a balcony. Indoor cannas, thanks to their vibrant colours and high decorative effect, become a center of any winter garden. On top of that, a dormant period of cannas is just 2 months, for the rest of the year they will gratify you with beautiful flowers and leaves.
You can grow canna in a pot like any other indoor plant, also you can transplant a canna from your garden into a pot. To do that, you need a tub or a pot 50 cm in diameter, and don't forget to apply insecticide to the soil before you pull the canna off to avoid bringing pests into the house.
Taking Care of Indoor Cannas
Handling of cannas indoors is much easier than outdoors. You don't need to spray them with water, control weeds or loosen the soil. Also, you don't need to fertilize indoor cannas. Put the plant in a light room and moisten it when needed with settled water. Once a while wipe the leaves with a damp sponge, like this the foliage will stay colourful and beautiful also outside of the flowering period.
Cannas After Flowering
When your indoor canna has stopped with blooming, it needs to go to its dormant period. Reduce watering, then stop moisten the plants at all. Cut leaves off at the height of 10 to 15 cm from the ground. Place the pot into a cool, dry room with the air temperature 10 °C or warmer. When the winter is over, take the rhizomes out of soil, divide and plant the divisions again. You can either keep them growing indoors, or plant them in the garden.
Same for outdoor cannas: they don't need much moisturization after they stop blooming. Slowly stop with watering and hill up cannas to protect rhizomes from freezing. Otherwise they are going to root during winter. After first frosts cut the stems at the height of 15 to 20 cm, and take the rhizomes out without shaking off the soil.
Storing Over Winter
Before the first frost arrives, dig cannas out in their soil balls, and move to the room where they will be stored until spring.
The best storage for cannas is a cool room with a moderate level of humidity and diffused light.
Put rhizomes into a box and strew them with a mix of peat, sand and soil with wood shreddings (non-coniferous). The humidity of the mix needs to be around 50 %, the temperature – 6 to 8 °C.
Storing cannas over winter requires a regular check of rhizomes. If you find a rotting root, cut the affected area off, and apply iodine on the cut. Monitor the humidity level and protect the rhizomes from temperature differences.
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You can also store rhizomes in a fridge. Dig them out before frosts, rinse off soil and dirt, keep for 24 hours in a disinfection solution and dry well. Then wrap every root in a sheet of paper and put them in the bottom part of a fridge (where you normally store vegetables). From time to time you need to check if rhizomes are not rotting. Some gardeners store rhizomes covered with dry ground in a plastic bucket at the balcony. If it gets really cold, just take the bucket inside, and keep it next to the balcony door, until biting frosts are over.
Another way to store canna rhizomes over winter is to keep them in soil, in pots at the room temperature 15° C or lower. For example, at the veranda, or in the attic. In this case you need to moisten the soil a couple of times per months.
When there is no cold winter in your region, you can store rhizomes in the garden. Dig roots out, put them on the ground and cover with wood shreddings. Ensure that there is no wind or water in the spot where you store canna roots.