Canna from Heaven11 January 2016 Graham Ross
I first noticed cannas when I was about 10 years old. While chasing a cricket ball, I stumbled into a huge mass of tall, ragged leaves and colourful flowers in our local park.
This park was filled with beds of roses and enormous, 130-140m long beds of cannas. The council staff came along every year and chopped the cannas to the ground and within what seemed like weeks, they were spearing out of the ground again.
Photo - Acambium64 / Shutterstock
So for a long time, I didn’t grow cannas because I considered them common park plants. But later on, when employed as the head gardener of that very same council, I quickly came to appreciate the beauty of these South American native plants. Back then, canna was a 1.5m, lush and leafy green plant, boasting the odd purplish-green leafed variety. All had huge velvety flowers of intense red, yellow, orange or pink. And that was how they remained until Canna ‘Tropicanna’ came along in the 1980s and started a revolution; now everyone is growing and loving the new cannas. And why not? They’ve a lot going for them.
The Modern Cannas
Every gardener today can grow and appreciate cannas - their vigour, fabulous floral display and stunning foliage colours. Canna flowers have always shown intense colours but the old range has been increased to include apricot, cream, mauve, speckled and streaked bi- and tri-colours plus larger flowers with crinkled petals. Some flowers even enjoy a luminescence in the petal and all have a repeat flowering habit that makes for 6-7 months of striking parade in the garden.
But with Canna ‘Tropicanna’ came a completely new era in leaf colour displays. Never before had we such a plant that screamed for attention with such compelling foliage colour – bronzes, purples, variegated creams and greens and even blacks. Indeed, the leaf and flower colours of this complex group of hybrids have attracted a legion of cottage gardeners. No wonder Aussie Plant Finder, Publisher: Florilegium, RRP $24.95, lists over 200 varieties, all with a wide range of sizes growing from 0.5 to 2m.
You Can Grow Cannas
Cannas will grow just about anywhere regardless of climate. If need be, they’ll even thrive on neglect - as long as you give the perennial rhizome root (that’s the thick fleshy part of the root), a chance to recover during a winter dormancy, after a stunning six months of flowering in spring, summer and autumn.
How do you do that? Well, I was recently in a beautiful garden in Tenterfield, NSW, where I saw many elegant cannas, all new varieties, growing to perfection. That garden receives on average 50-70 days of severe frost in winter. The secret? A thick layer of straw, mushroom compost or leaf mulch to protect the rhizome from freezing in winter and then feeding with manure in spring.
Cannas grow easily in large half barrels or ornamental tubs but the soil needs to be a quality potting mix with added slow release fertiliser and manure mulch. And that mulching isn’t optional. Cannas are filled with water so if they are allowed to dry out on a hot summers’ day, you can forget the flowers. Mulch retains the moisture in the soil and keeps the roots cool and the plants turgid.
In the garden, cannas need light clay soils with aged cow manure and compost added. If your soil is sandy, add compost or straw with cow or horse manure to retain moisture. Some gardeners find success in planting cannas around water holes, in poorly drained, moist soils and in ponds and water features.
Since many new cannas are tall, around 2m, with delicate flowers, they are easily damaged by strong summer storms and winds, so, select a protected spot in the garden. Also, the sunnier the aspect, the better the flower quality - cannas will tolerate some shade but the leaf display takes over from the flowers.
At planting time, improve the soil with manure and a handful of organic-based pellets. These should be dug in to a depth of 20cms. Make a 5cm depression in the soil and add a spoonful of Rainsaver Water Crystals converted into jelly. Place the new plant in the base and back fill, leaving a small section of old stem just above soil level. Nurture the plant with water that has a seaweed solution added. If slugs and snails appear when the new shoots arise, protect them with pet-safe pellets such as Multiguard.
Cannas benefit from a regular supply of organic and artificial fertilisers, and will respond even further to additional feeding during spring and summer.
Nutrients are best supplied by a monthly sprinkling of Organic Life, Amgrow’s Organic Extra, Dynamic Lifter, or any good pelleted manure. I always add a manure-enriched compost around the newly shooting plants in spring to ensure strong growth. When the flower buds appear, take the time to water them with a soluble fertiliser such as Thrive for Fruit and Flowers[corr] or Better Bloom and enjoy an even better floral display.
Care and propagation
Some books recommend you lift cannas in cool climates during winter. If you apply a thick layer of mulch over the roots in autumn, this will protect the plants from freezing. In all areas, the old spent flower stems and leaves should be cut down to within 10cm of ground level at the end of autumn. This short stem ‘handle’ makes lifting and dividing. If you have a large established clump, divide it in late winter or early spring. Dig down below the roots with a garden fork and remove excess soil. Trim off spent leaves and prune back roots. Divide the clump, ensuring each piece of plant has some fibrous roots and at least a 10-15cm length of healthy rhizome and one healthy plump ‘eye’ or growing point.
In The Garden
How do you ensure your cannas look great? Firstly, when planting them out, consider grouping 5-6 plants of the same colour in the one area. This means the colour display will be large and dramatic. Even if you only have space for two groups, it is better to limit your colours but increase the quantity of each variety.Also consider using the different heights of varieties to your advantage - lower, medium and taller cultivars in graded plantings work wonderfully in circular and kidney-shaped garden beds. And try combining large beds of bold cannas of a limited range of colours with other feature plants. Considerplanting your cannas with flowering agapanthus; [itals]Hemerocallis, daylilies; [itals] Kniphofia, red hot pokers; penstemon and [itals]Perovskia, Russian Sage. Add any of the ornamental grasses, such as [tials]Dianella ‘Border gold’ or D. ‘Border Silver’, [itals]Pennisetum, [itals]Miscanthus or [itals]Cordyline ‘Red Fountain’ or colourful shrubs. If you select your partners for your cannas carefully, contrasting foliage colours and textures, you’ll be well on your way to an award-winning display!