Beautiful Low Maintenance Cannas
Because of their long bloom time, tolerance of hot weather and exotic tropical look, canna lilies are a favorite of Augusta gardeners. Since they are also fast growing, they provide immediate impact, growing from two to 10 feet tall, depending on the cultivar. Their huge, iris-like flowers open and continue to bloom until frost, sometimes till late December.
Canna blooms are typically red, orange, yellow or any combination thereof. Leaves are usually solid green, with some cultivars boasting brown, maroon, bronze or green leaves variegated in white, cream, pink or red. One of my favorite varieties is Bengal Tiger, which reaches five to six feet in height with brilliant orange flowers and green and white striped leaves.
Cannas are an ideal choice to brighten up any sunny location in your landscape and may, in fact, successfully be the focal point. They are also a good choice for planting in mixed borders, massed alone in garden beds or in small groupings with other plants and they are most magnificent when planted in mass. Their versatility is even more attractive when you consider their low maintenance.
As a rule of thumb plant a minimum of 10 cannas with borders of different flower colors and they are a perfect complement to fine-textured plants such as ornamental grass.
Cannas are also well-suited for growing as single specimen plants when combined in large pots with other flowers and plants of varying heights. And they can even be effectively used in sunken pots in water gardens.
Cannas flourish with plenty of heat and water. They grow best in full sun (six hours minimum), but will tolerate partial shade. They prefer loamy rich soil and an abundant supply of nutrients. So when planting incorporate two to four inches of compost in the bed.
Since most Augusta soils are less than ideal, keep in mind that cannas will grow in almost any of them as long as you provide proper fertilization and irrigation. They like moist slightly acidic soil and will thrive even in boggy conditions, but will not tolerate alkaline soils.
For best results provide moderate, frequent fertilization (5-10-15 is a good choice at two pounds per square foot) beginning in early spring and continuing on a monthly basis to assure prolific growth and flowering.
Cannas are grown throughout the United States, but in northern climates their bulbs must be dug up and replanted the next year, which isn’t necessary in Augusta. If properly cared for in this climate, they will continue to grow and bear flowers throughout the winter. When winter is over, they can be divided and transplanted directly into beds.
Cannas are best planted in the spring, from mid-March to mid-April, 12 to 24 inches apart, depending on the cultivar height, placing the long part of the bulb horizontally in the ground with the eyes up, if visible. Since canna rhizomes don’t have a top or bottom, there’s no need to worry about placing them upside down.
Removing spent blooms or deadheading is helpful, but not essential for continuous blooms. Remove the part of the stem that bore flowers after the flowers have withered. Usually a second flowering shoot, growing from the node just below the terminal flowers, already will be halfway in flower. Also remove this shoot when its flowers wither. Another flowering shoot will soon develop on the node below the second shoot. If the first and second shoots are not removed, much of the nutrition will be used for the development of seed pods and the flower cluster on the third node will usually remain dormant. Regularly removing spent shoots diverts nutrition to the young flower shoots and assures profuse flowering for a long period of time.
Like most bulbs and perennials, cannas need dividing over time to keep them from becoming too crowded and producing fewer blooms. On average, they should be divided every two to three years—in late winter, early spring or fall in Augusta. This is also a good time to add organic matter back to the soil. For best results, try to break the bulbs so that there are at least three eyes per section. If a few small pieces are left over plant them too.
The dug up bulbs should be cleaned off and rinsed in a bleach solution (one part bleach to nine parts water) to reduce the chances of disease. You can then transplant them to another area of your yard or share with friends and neighbors.
Cannas, for the most part, are pretty much pest free. Their overall biggest nemesis is the canna leaf roller, which is a larva that will chew straight rows of holes on the leaves. Most types feed as solitary caterpillars, but some feed in groups under a netting of their own silk. Solitary types feed on leaves by rolling, folding or tying them together before eating and are active at night. Infested leaves will appear shredded from the cocoon-like web. Young leaves will be so damaged that they can’t open and may die. Infested plants are unable to bloom and have an unattractive appearance. Without careful monitoring, it is easy to miss the signs of the first generation of caterpillars because they are already inside the tightly rolled leaves below the visible growing point. Damage from the second and third generations is more obvious and more extensive.
Once the caterpillars are inside the rolled leaves, they are hard to control without the use of insecticide. Affected leaves can be cut off or you can unrolled them to physically remove the caterpillar, though most gardeners prefer to use an insecticide. Systemic insecticides work best. There are a variety from Bayer Advanced that contain either disulfoton or imidacloprid that you either spray or mix with water and water in around the plants. Acephate is another systemic that can be sprayed on the plants. Or for organic options you can try Bacillus thuringiensis (Bt) or insecticidal soaps.
It is important to discard dead foliage during the winter because the larvae of canna leaf rollers overwinter in dead leaves. By removing the foliage the majority of the insect residue will be removed.
Occasionally slugs and snails feed on cannas, leaving large holes in the leaves, but they prefer the tender young leaves that have not yet unfurled. These pests are easy to spot because they leave slimy trails on the ground. Commercial baits provide effective control and removing debris around the plants will eliminate their daytime hiding places. Beer placed in jar lids or the tops of plastic champagne glasses will also catch slugs and snails.
Less often cannas may suffer from canna rust, a fungus that affects their leaves, and also botrytisblight, a fungus that affects their flowers. In both cases simply remove the affected leaves or flowers.
You may also see small parallel tears on leaves that look like insect damage, but this is actually the result of inconsistent watering, which can be prevented by watering plants during dry spells.
So while cannas are not completely without need for maintenance, overall they are one of the least demanding and most beautiful plants you can grow in Augusta.