For height, drama and a tropical look in northern gardens, nothing beats canna lilies. Native to tropical and semi-tropical areas of North and South America, canna lilies evolved along damp, semi-shady riverbanks. They are perennials in parts of the southern United States, but in northern climates they are annual plants for the back of a border or large containers.
Are They Lilies?
Cannas (Canna x generalis) are not true lilies, and they grow from rhizomes rather than bulbs. Rhizomes are modified stems that grow horizontally underground, as the rhizome grows it develops eyes that grow upward. The leaf structures rise from eyes on the rhizome, growing as tall as 4 feet. Canna leaves are large and may be variegated or a deep burgundy color. In midsummer, the plants bloom with dramatic flowers that resemble the blooms of an iris.
Cannas can be grown in the ground or in a container. If you choose to grow them in a container, make sure it is a large one—at least 15 inches in diameter and preferably 18 or more. The big container matches the size of the mature plant and grounds it enough to prevent the plant from tipping in the wind.
Canna Planting and Care
Choose firm, sturdy rhizomes. Wait to plant them until the danger of frost is past—they prefer soil that is at least 60 degrees. Dig a trench in the soil (or in the container) 4 inches deep and lay the rhizome in it with the eyes pointing upward. Then, cover the rhizome with soil or compost. The eyes should be 2 inches below the top of the soil. If you are planting more than one canna, place them 8 to 12 inches apart.
Cannas will need regular watering and will grow taller and flower more with monthly fertilizing with a light fertilizer—look for a liquid feed with the numbers 5-10-5 on the bottle.
During the MSHS Bulb Sale, two popular cultivars of canna lilies are available. 'Australia' is a striking plant with dark burgundy, almost black large leaves and red flowers. This is a real attention-getter in the garden or on your porch or patio. 'Pretoria' has variegated leaves and orange flowers. Both are stunning and are available for online order through April 16. Buyers can have plants shipped to them or they can pick them up at the MSHS office in Roseville, MN, in early May.