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Summer Flowering Bulbs

by Don Janssen, UNL Extension Educator

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Summer flowering bulbs which are tender to weather conditions can add beauty to the home landscape. Many have small flowers and need to be planted in groups or beds to show off their flowers. Some have large flowers and may need to be staked to be properly displayed.

There are many tuberous types of begonias available. Traditionally, we think of the large camellia flowered types with various color combinations grown from tubers. But also available are tuberous types grown from seed. These seed-started types are known as 'Nonstops'. Flowers are smaller but produced in profusion.

Common to begonias is a soil mix with plenty of peat moss and perlite for good soil drainage. The tubers can be placed directly in pots or flats of a peat perlite mix and kept at 68 to 75 degrees F for sprouting to occur. Once the pink shoot starts to grow, keep plants in a sunny area. Plants should be kept evenly moist but not wet. Fertilize every two weeks avoiding fertilizers with ammonia salt sources because crinkled and curled leaves can occur.

Cannas are bright, bold-leafed tropical plant with red, pink, yellow, orange and cream flowers. Traditionally, canna rhizomes will produce plants from three to eight feet tall.

Direct planting of the canna rhizome into the garden can be done in mid-May. The planting site should be well drained and in full sun. Amend the planting site with peat moss or compost. Space plants 18 to 24 inches apart. Water plants thoroughly after planting and fertilize as shoots emerge using 5-10-5 or 5-10-10 at the rate of three to four pounds per 100 square feet. Apply fertilizer once a month and be sure to water after application. Remove dead flowers to encourage more to come on the stem. Once frost has killed the canna tops in fall, cut off the dead tops and dig rhizomes. Use care in digging. Hose off soil around rhizomes and store inside at 45 to 50 degrees F. Do not allow rhizomes to freeze.

The caladium is a bright, bold-leafed plant that is grown mainly for its foliage in both sun or shade. It produces broadly arrow-shaped leaves in striking color combinations of reds, pinks, greens, whites and bi-colors. Flowers are insignificant and can be removed when first noted.

Start the potato-like tubers in early March in a peat type soil. Plant tubers in a six- to eight-inch pot, knobby side up, about two inches deep. Keep soil moist during the rooting period. It is essential to provide bottom heat of 75 to 80 degrees F to facilitate sprouting of tubers. Move plants outdoors after all frost is past to a shady, wind-protected location. Water as needed especially on hot days.

From July to October, dahlias produce two to eight foot plants with flowers 8 to 12 inches across. Seed-started cultivars flower earlier with three to five inch flowers. A wide range of colors, except blue types, are available. Tubers can be started indoors, but are generally planted directly in the garden in May in a well-drained sunny location. Plants should be staked at planting time because they will require support for the large flowers.

Feed lightly at first because heavy feedings may delay flowering. Prune side stems allowing only one main stem.

Gladiolus is produced from a corm. Gladiolus come in a wide color range and can grow from one to five feet. Glads make excellent background plants as only one flower stalk is produced per corm. It is best to plant corms outdoors over a two month period starting in early May to stagger the bloom period. Set corms four to five inches deep and six inches apart in a well-drained sunny location.

A 5-10-5 fertilizer can be used at planting time and again as the flower spike develops. Water as needed. Staking may be needed. Harvest flowers leaving a minimum of four leaves on the plant to restore the corm.

This resource was added June 2008 and appeared in the Lincoln Journal Star Newspaper Sunday edition. For information on reproducing this article or using any photographs or graphics, read the Terms of Use statement


University of Nebraska-Lincoln Extension in Lancaster County is your on-line yard and garden educational resource. The information on this Web site is valid for residents of southeastern Nebraska. It may or may not apply in your area. If you live outside southeastern Nebraska, visit your local Extension office

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