Canna Lilies Vs. Calla Lilies

The bright tropical flowers and bananalike leaves of canna lilies (Canna spp.) contrast with the more subtle whites, creams and yellow, pink or purple blossoms of calla lilies (Zantedeschia spp.). When deciding which flowers to plant in spring for summer bloom, these rhizomes are easy-care options for gardens in U.S. Department of Agriculture plant hardiness zones 7 through 10.

Though they are called "lilies," both cannas and callas are not members of the lily or Liliaceae family. The cannas consist of 10 to 12 species in the Cannaceae family, while the approximately eight species of callas are in the Araceae family. Both cannas and callas have a multitude of hybrids and cultivars.

While both grow from rhizomes, you may ask, "What is the difference between canna and calla lilies?" Color is one major difference, with cannas featuring bright flowers in colors ranging from yellow to burgundy, while the familiar callas are often seen with white spathes that surround the small yellow flowers on a spadix, though cultivars with yellow, pink, purple and multicolored spathes are also available. Cannas have large, bananalike or paddle-shaped leaves in green, burgundy or variegated colors. Callas have long, arrow-shaped green or green and white leaves.

Both cannas and callas prefer sunny, moist soils and thrive along ponds and waterways. Cannas may be sunk in pots up to 6 inches deep in ponds, while callas tolerate wetter conditions in up to 12 inches of water or mud.

Choosing cannas or callas for the garden depends on several factors, including your personal aesthetic. Cannas, depending on the species and cultivar, may grow from 18 inches to 12 feet tall and up to 8 feet wide, while the 1- to 3-foot-tall callas are suited for smaller spaces. Both species may be grown in containers, but cannas need 18- to 24-inch-wide pots due to their larger size and to help prevent tipping when the plants reach their mature height.

For tropical flavor, the brilliant flowers and large leaves make the large canna cultivars a good backdrop for smaller flowers and plants while hiding ugly walls and fences. Callas, on the other hand, are smaller with beautiful but more subtle flowers and are suited to cottage and formal gardens and around garden ponds.

Cannas prefer well-drained soils, while callas thrive in muddy locations where canna rhizomes would rot. Both plants should be lifted after the first frost when the foliage dies back. Though the rhizomes are considered hardy to USDA zone 7, to ensure winter survival, dig up and store both cannas and callas for the winter in zones 7 and below and heavily mulch in zone 8.

Both canna lilies and calla lilies thrive in warm, moist conditions. While this is a plus for a gardener plagued with moist to wet soils, both plants can become invasive when planted near marshes and waterways. Remove the spent flowers after blooming to prevent seeds from forming and spreading the plants outside of the garden. Control rhizome and tuber spread by planting in containers and avoid planting in gardens near wetlands, ponds and waterways.

While cannas are nontoxic and the rhizomes were once used as a food source by the indigenous peoples of the Americas, calla lilies are a different matter. All parts of callas are considered highly toxic and should be kept out of the reach of children and pets. The plant contains calcium oxalate crystals and if ingested, causes severe burning and swelling of the mouth, including the tongue, lips and throat as well as gastric distress and diarrhea. Wear gloves and safety goggles when working with callas and avoid touching your mouth or eyes. Wash thoroughly with soap and water after handling the plants.