Calla and canna lilies
Canna and calla lilies grow well in hot sites throughout Minnesota. Though the names are similar, the plants are not that similar, and neither is an actual lily!
Cannas and calla lilies are not hardy in Minnesota, but can be grown as annuals, houseplants or their rhizomes may be overwintered inside.
Cannas and calla lilies come in many different flower colors and leaf types, and make a dramatic statement in the garden.
Calla lilies or callas (Zantedeschia species) are not true lilies. They are related to jack-in-the-pulpit and caladium. Unlike jack-in-the-pulpit, they are not hardy in Minnesota. The tuber-like rhizomes must be dug up and stored inside over the winter.
Callas have a broad, trumpet-shaped flower called a spathe that wraps around the finger-like spadix. The spathe is actually a modified leaf and may be white, yellow, peach, orange, red, pink, purple or bicolored. The spadix holds the tiny, true flowers. Its leaves are arrowhead-shaped and solid green or green with silver or white flecks.
Zantedeschia aethiopica, the white calla, is native to Africa where it is considered a weed. The flowers can be quite large, with a spathe up to 10 inches long and a yellow spadix. It has also become naturalized in warm parts of the U.S., such as in California, where it is an invasive species. Because it is not hardy in Minnesota, invasiveness is generally not a concern here.
Callas may be grown as houseplants, in a sunny location, but for the best results, plant callas outside and enjoy them indoors as cut flowers. They should bloom mid to late summer for about a month.
Callas thrive in a deep, moist, rich soil in full sun. They will grow in part shade, but will not bloom as well. White callas will grow in boggy or alkaline soils.
Set rhizomes four to six inches deep and one to two feet apart. Fertilize in spring after planting them, using a 5-10-5 or 5-10-10 fertilizer.
Canna lilies or cannas (Canna x generalis) are native to tropical and subtropical areas. They are not hardy in Minnesota. Like callas, their rhizomes must be dug up in the fall after frost has blackened the foliage.
Cannas grow 1 1/2 to 5 feet or more, depending on variety. Their large, glossy leaves are 6 to 12 inches wide. The exotic leaves come in bronze, purple, burgundy, bright green, dark green or even multicolored, so cannas are ornamental even without their flowers.
Their blossoms are clustered at the top of flower spikes which can be up to one foot long. Blossom size varies with the species planted. Cannas are available in red, rose/pink, yellow, orange, salmon and red with yellow.
They make a very attractive planting for a large container, in raised beds or as background plants. The flowers of some varieties are even attractive to pollinators such as bumblebees and hummingbirds.
Cannas may be started indoors by planting them three to four inches deep in pots, then transplanting them outside. They will also bloom well if planted directly into the garden as soon as the soil has warmed and danger of frost has passed.
Plant the rhizomes 3 to 4 inches deep and 1 1/2 to 3 feet apart. Cannas grow best in full sun and hot weather, providing they have adequate moisture and a soil high in organic matter. They will bloom in a warm site that gets part day sun, such as along a house wall. They bloom mid-summer to frost.
In the fall, dig up the rhizomes, cut the stems back to 2 to 3 inches, and let them dry. Leave them in a box in a cool part of the house where they will not freeze, such as a basement where the temperatures range between 40 to 50 degrees.
Every few years, the rhizomes may be divided. When dividing, each piece must have an eye, or growing point, on it. Let the cut-up rhizomes dry for a few days before planting them.
Reviewed in 2018