Reader, I developed a bit of a crush on this Victorian era plant. They're probably too thirsty for my garden--although many plants can do with far less than we think--and the tropical look just doesn't fit, but I wouldn't begrudge anyone a canna or five, especially if they're put to good use.
Horticulturalist John Schustra of Greenwood Daylily Gardens says if you've got a spot where water pools in your yard, put in cannas. They'll slurp up the water and filter out pollutants. (Note: pooling water could be a sign you're overwatering your yard.)
Nurseries, including Schoustra's, commonly use cannas in bioswales to keep polluted water (i.e. enriched with fertilizers) from running off their lots.
However, if you're looking for a place to cleanse grey water, a patch of cannas could be a nice fit. "They're greedy pigs," says Schoustra, "They don't have to have a ton of water and a ton of fertilizer, but if it's there, they will take it."
Or you might try what I've done with quite a few conventional garden plants: cut back water and see how they do.
"I don't look at them as being that thirsty," says Randy Baldwin of San Marcos Growers. "They're tough plants. They grow better with more water, but they have durable rhizomes." Baldwin and Schoustra recommend the orange variety 'Intrigue' as especially drought-tolerant.
Schoustra has crossed 'Intrigue' with another variety to come up with this beauty, called 'Chocolate Inferno.'
Schoustra advises giving cannas abundant water when they most need it--summer months--then cutting back in the fall. "The first week in September there's a little clock that goes off in most perennials in Southern California," he says, "and they stop having so much sugar in their system, they start storing starch for the winter, and their water needs drop off a great deal."
A suite of viruses has beset cannas in recent years. They mottle canna flowers and foliage and generally weaken the plants. Randy Baldwin says the variegated varieties are especially prone to infection.
But wait, there's more! To find out the secret to robust canna blooms, read my short LA Times piece.