Canna lilies take the fall in garden experiment

By Marianne C. Ophardt, Special to the Herald

KENNEWICK -- Last year, I boasted about my gorgeous container gardens.

This year, I tried something different and the planters were nothing to brag about

Perhaps it's karma for last year's gardening hubris, or maybe it's simply the yin and yang of gardening.

So what happened? This past spring I decided to try canna lilies for the tall element in the pots. Two pots had traditional red canna lilies and two others had the exotic Tropicannas (canna lilies too) with gold-salmon flowers and striking red, purple, green, and gold variegated leaves. At the base of the cannas, I planted both dark purple "Blackie" and chartreuse "Marguerite" sweet potato vines and purple Wave petunias. I had thought the multicolored Tropicanna foliage would tie everything together.

It should have been a great combination, but all the cannas fizzled. Even though they're rated as full sun plants, the extremely hot and exposed conditions in front of my west-facing house were too much for them. The canna foliage tore in the wind and scorched in the heat.

Also, the new drip irrigation set up in the pots may be partially to blame for my failure. I suspect the drip irrigation may not have moistened the soil as thoroughly as watering by hand did last summer.

Now that fall is here, I plan to dig up the canna rhizomes and try again next year. However, I'll probably plant the cannas in the pots on my patio where they'll get a little less sun, heat and wind than they did in front of the house.

Fall digging of the rhizomes is a must. Cannas are not considered hardy in our USDA hardiness zone (Zone 6) so it's important to protect the rhizomes from freezing. Some local gardeners say they've been successful overwintering them in the ground. This may be explained if they planted their cannas in a warm micro-climate zone in their landscape, perhaps close to the house where the soil temperature doesn't go below freezing.

However, if you want to make sure you have cannas next year, dig them up.

It's OK to wait until after frost kills the tops before digging the cannas up. The process involves cutting the stems off, leaving only about 2 to 3 inches at the base. Dig up the rhizomes by carefully lifting them out with a garden fork. It's likely that the rhizomes will break in several places, but that's OK. Shake or wash off any soil sticking to the rhizomes, then trim off any roots or shriveled portions of rhizome before storing them.

Next, it's important to let them dry off for a few days. Then place the dry rhizomes in paper bags. Don't forget to write the flower color on the outside. Store them in a cool (40 to 50 degrees) spot where they won't freeze.

In the spring, it's a simple task to divide the rhizomes by cutting them into pieces. The buds that will sprout into the new stems and leaves are located at the base of the old stems. Each newly cut piece should have several buds on it. Allow the cut end to dry a day or two before planting.

I'm already thinking about what to plant in my front pots next year. It definitely should be something bright and bold -- and able to withstand heat and wind. Maybe orange Profusion zinnias and bright Inca yellow marigolds would be a good choice. I have all winter to decide.

* Marianne C. Ophardt is a horticulturist for the Washington State University Benton County Extension Office.

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Saturday, Oct. 10, 2009

Canna lilies take the fall in garden experiment

By Marianne C. Ophardt, Special to the Herald