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Cannas can add new dimension to flower gardens

Published: Sunday, July 8 2012 2:53 p.m. MDT

Cannas Maroon  (larry sagers) Cannas Maroon (larry sagers)

Cannas are one of my favorite summer bulbs. The most compelling reason to grow cannas is for the exotic tropical looking leaves. Few plants rival the cannas' striking foliage that comes in rich shades of red and green, maroon and bronze as well as numerous variegated patterns. They grow broad, flat, alternating leaves that grow out of the stem in a long narrow roll and then unfurl.

The plants have many wonderful characteristics. These include interesting flowers that come in several colors ranging from dark red to light green. They grow quickly and are wonderful as backgrounds for bedding plants and other garden selections. Consider combining them with castor beans, caladiums or other large leafed plants.

Although they are often called canna lilies, they are not true lilies. They are related to gingers and bananas. Canna is the only genus in the family Cannaceae. Interestingly enough, cannas are a very rich starch source and are an important agricultural plant in some areas of the world.

Canna flower at Spence Mortenson garden (larry sagers) Canna flower at Spence Mortenson garden (larry sagers)

The plants are tropical in origin but they grow well during the summer throughout Utah. Their name comes from the Celtic word for a cane or reed.

Cannas became very popular in Victorian times as garden plants. All cannas were once native to the Americas from South Carolina around to southern Texas and then south to Argentina. Some cannas likely came to Europe via India and Africa.

Some canna cultivars are large and need plenty of room, while others are more compact and better adapted for smaller growing areas. Garden cultivars usually range in height from 24 to 60 inches but some species will reach 10 feet. They make a good background or even a temporary screen in the garden beds.

Cannas thrive in warm, sunny locations. They will thrive with the same conditions as corn — warm, well-drained soil with plenty of decayed organic matter. They are tender, so they cannot be planted until danger of frost is past and the soil is warm. Protect them from high winds as the leaves are easily shredded.

Canna flower at Spence Mortenson garden. (larry sagers) Canna flower at Spence Mortenson garden. (larry sagers)

The plants are readily available from nurseries but many gardeners save their own from year to year. Planting them directly into the soil is the easiest method, but since they take longer to develop, starting them inside in pots gets a jump on the gardening season.

Most gardeners start with part of an old tuber containing several strong buds. These can be divided to single buds — but weak buds make weak plants. For large vigorous plants, use large clusters of rhizomes.

Cannas grow from these swollen stems that are correctly called rhizomes. The plants spread as these rhizomes grow so a plant can triple in size or even grow much larger over the course of the summer. Larger plants need 18-36 inches between them for growing room.

Cannas plants are not very fussy and will grow with little care. If you are looking for maximum growth, give them plenty of nutrients and moisture. They will grow as pond plants in one inch or more of standing water, but they grow equally well in a terrestrial environment in soil.

Canna Australia Pretoria (larry sagers) Canna Australia Pretoria (larry sagers)

The abundant foliage develops quickly so make regular applications of fertilizer to keep them growing well. Although they have few pests, slugs and snails will damage plants as will spider mites so watch for these pests and control them before they cause serious damage.

Cannas are usually free of diseases but occasionally they are affected by specific plant viruses. These cause spotted or streaked leaves when they first start but eventually cause stunted growth and twisted and distorted blooms and foliage. Dig and discard affected plants to prevent these diseases from spreading.

There are more than 60 cultivars available, providing a wide choice of flower colors and leaf colors, as well as different sizes for the plants. Historians think there were once hundreds of canna cultivars available but many of these are now extinct.

Canna Tropicana (larry sagers) Canna Tropicana (larry sagers)

Flowers are not the dominant parts of these plants but add an extra sparkle in the landscape. Remove the spent flowers to keep new blossoms developing. Some cannas are self-cleaning, meaning they drop spent blooms and do not need mechanical deadheading.

A bonus from the flowers — particularly red ones — is that they attract hummingbirds.

Use these plants to add a new dimension to your flower gardens. Choose the size and colors that blend well with the other garden plants.

Larry A. Sagers is a horticulture specialist for the Utah State University Extension Service at Thanksgiving Point.

Garden tips

Canna flower Longwood Gardens, PA (larry sagers) Canna flower Longwood Gardens, PA (larry sagers)

Red Butte Garden July 12 and August 2, 7- 8:30 p.m. Take a walk to see what's blooming in the garden with a garden guide. Wear comfortable clothes and walking shoes. Meet in the Visitor Center courtyard. Registration required online or by phone (801-581-8454). Members must call to register. Regular garden admission, members free.

Temple Square Free Garden Tours on weekdays and Sundays through September. These public tours require no reservations. Private tour groups can call 801-240-5916 to schedule.

Tour Schedule: Tour of the Church Office Building Plaza is Monday-Friday 11 a.m. or on Wednesday evening at 7 p.m. Meet at the south doors of the Church Office Building Tower. Sunday morning 10:30 a.m. following the Tabernacle Choir Broadcast. Visitors meet the guide at the East Gates of Temple Square.

(2) Tour of Conference Center Roof Gardens. Monday—Friday 10:00 a.m. Meet inside Door 15.

Complimentary one-hour Garden Talks in the Park, July 11 at 8 pm. "Creating Water Wise Beauty in the Garden" at Brigham Young Historical Park, North Temple and State Street. The talk is free and no tickets are required.

Garden tips

Red Butte Garden, July 12 and Aug. 2, 7- 8:30 p.m. Take a walk to see what's blooming in the garden with a garden guide. Wear comfortable clothes and walking shoes. Meet in the Visitor Center courtyard. Registration required online or by phone (801-581-8454). Members must call to register. Regular garden admission, members free.

Temple Square free garden tours on weekdays and Sundays through September. These public tours require no reservations. Private tour groups can call 801-240-5916 to schedule.

Complementary one-hour Garden Talks in the Park, July 11 at 8 p.m. "Creating Water Wise Beauty in the Garden" at Brigham Young Historical Park, North Temple and State Street. The talk is free and no tickets are required.

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