These big-leafed tropicals are actually pretty tough and can take a few frosts without suffering much damage.
Here are a few cannas that I’ve been saving from year to year.
Note the purple sweet potato vines (at the base) that I planted with these cannas in May.
When you’re ready to bring your cannas indoors for the winter (usually mid- October to mid-Nov.), you can either carry the whole pot indoors or cut back the foliage and dig up and save the rhizomes/tubers.
As I’ve said before, I don’t have a lot of room for large pots of plants around the house. So first I cut back the stalks and leaves to a height of just 2 or 3 inches from the ground.
Then I dig up and separate the various clumps that have grown and multiplied over the summer. Cannas like to be potbound, so sometimes you really have to hack into them to get the tubers to come apart and out of the ground.
Here’s a look at the clumps just out of the pot. See those long skinny tubers in front? Those are the “sweet potatoes” that the vines have been growing all summer. I saved them, too, to see if I can bring them back next spring.
I let the cannas dry out on newspapers for a few days, then box them up with a few sheets of newspaper in my unheated basement for the winter. I try to remember to check on them every month or so to make sure they haven’t dried out completely.
Want to learn more about cannas? Here’s a story I wrote a couple of years ago for one of our Home&Design magazines:
“The more you garden, the more you realize that foliage can be as important as flowers. Many of the showstoppers in the spring flower garden – tulips, lilacs, irises, peonies – bloom their hearts out for a couple of weeks, then leave you with dull green or brown foliage for the rest of the summer. But a plant with interesting leaves can earn its keep for up to three or four seasons.
For striking, flashy foliage in a relatively short amount of time, it’s hard to beat the tropical allure of canna lilies. Some grow up to 7 or 8 feet tall, adding a stately, vertical element to the late-summer garden.
You just need a few cannas, with their broad, pointed leaves and odd spiky blooms, to add drama and interest to a perennial border or in terra cotta pots on the terrace or deck.
“What a great plant to put in a container,” says Mike Ruggiero, former senior curator at the New York Botanical Garden and now the senior horticulturist at Matterhorn Nursery in Spring Valley. “I like the bold leaves, not the flowers. Just cut the flowers off – you don’t need them.”
Ruggiero, the co-author with Tom Christopher of “Annuals with Style” (Taunton, 2002), gave a lecture earlier this year at the Botanical Garden called “Eye-Popping Annuals,” and cannas earned a prominent spot in his talk.
Cannas are actually fleshy rhizomes (some call them summer bulbs) that can be dug up after a frost in the fall and saved for the following year, but many people simply treat them as annuals and get new plants each spring. Native to Asia and tropical parts of Central and South America, these herbaceous perennials are hardy in zones 8 to 11.
The craze for tropical plants that started in the late 1990s shows no sign of abating. Victorians grew cannas and other tropicals amid their elaborate flower beds, but cannas fell out of favor for much of the 20th century.
For Victorians, the color choice for canna leaves was mostly green, but varieties on the market now offer foliage that’s bronze, burgundy, purple or nearly black, or zebralike with striations of pink, green and yellow.
“How could people live without cannas?” asks Carol Klein, the author of “Plant Personalities: Choosing and Growing Plants by Character” (Timber, 2005) and a speaker on the same topic earlier this spring at the New York Botanical Garden. “They just bring this big `vroom’ to the whole border.”
Canna ‘Cleopatra’ – “my new all-time favorite this week,” Ruggiero says – offers dark green foliage with bronze-red variegation that varies from a streak to a full leaf. Each leaf going up the stem is different from the others, he says. The flowers are equally unusual and individualistic: Some are yellow, others are yellow with flecks of red and a few are half or fully red.
The exotic Canna Tropicanna has lush leaves in brownish-purple shades ranging from mocha at the base to nearly red at the tips, with striations of gold and a chartreuse center vein. The blooms are a brilliant tangerine.
Canna ‘Pretoria’ (also known as ‘Bengal Tiger’) features striped chartreuse leaves and orange flowers. Canna ‘President’ has glossy, blue-green leaves and rich scarlet flowers.
Some tastemakers find cannas much too gaudy and garish for the home garden, but what drama and fun a few will add to an otherwise tasteful and predictable flower bed.
Ruggiero may not care for the bright and blowzy flowers, but the big, complex blossoms are quite attractive to hummingbirds – and some humans. The asymmetric flowers have three petals joined in a tube at the base, along with three sepals and showy stamens. Color choices include apricot, canary yellow, scarlet, pink and deep orange, and some cultivars have flowers shaped like gladiolas or orchids.
Hundreds of hybrids have been developed over the years. Many of the new dwarf varieties, which grow to 2 to 3 feet tall, work particularly well in containers.
Cannas thrive in rich soil in hot weather and full sun. They are heavy feeders – give them lots of organic matter and fertilize them every few weeks throughout the season. They also need a lot of water, especially during dry spells.
Some cannas are so tolerant of wet feet that you can even grow them in pots in standing water, Ruggiero says. “But then you need a boat to deadhead them.”
Be sure to get them potbound first so that they don’t just float away, he warns.
Cannas are tough and sturdy plants – no need to stake them, even in fairly windy spots. Keep an eye out for hungry slugs, caterpillars and beetles, which also have a hankering for the attractive foliage.
To save your cannas for next year, cut the stems to about 3 inches after the first killing frost and dig up the clumps. Let them dry out for a few days and store in peat moss or vermiculite in a cool, frost-free spot for the winter.
Container-grown cannas can be brought indoors, cut back and left in their pots for winter. Either way, check the rhizomes once a month to make sure they have not dried out completely. Add a bit of water as needed.
In spring, get them started indoors in a soilless mix, then move the rhizomes to containers once roots have formed. Or plant them directly in the ground in early June, after the soil has warmed and temperatures remain above 50 degrees.
After a few seasons, new rhizomes will form or you can cut large rhizomes into smaller pieces for new plants.
Planted in a protected area and covered with a few inches of compost, some cannas will survive mild winters in the Northeast.
For all their assertive structure and bright color, cannas work surprisingly well with a broad spectrum of plants. Try them with ornamental grasses, crocosmia, dahlias and yarrow. Or mix them up with other tropicals such as elephant ear, banana tree, coleus, lantana, hibiscus, mandevilla or castor bean. Ã‚Â·
Cannas at a glance
Hardiness: Zones 8 to 11; elsewhere treated as an annual or tender perennial.
Light: Full sun to light shade.
Soil: Well-drained; rich in organics.
Bloom time: Late summer.
When to plant: Late spring to early summer.”