Gardening Articles: Flowers :: Bulbs

The Begonia Show-Offs (page 2 of 3)

by Chuck Anderson with Laurel Taylor

Seed Starting

Growing from seed rather than tubers is another option. You can grow thousands of begonias from one small packet of seed. Begonia seed is powder-fine, however, and requires sterile soil and careful control of temperature to grow. And plant size, quality, flower color, and form are also unpredictable. The plants take six to eight months from seed to bloom.

Temperature and Humidity

"I've grown tuberous begonias in many areas of the country--Hawaii, California, St. Louis, Philadelphia, Pittsburgh, and Ohio," says Frowine. St. Louis was the biggest challenge because of summer heat. If you shade them in the heat of the day and provide a place for them away from buildings that reflect heat on them, you can grow them in containers or in the ground."

Experts agree that this plant can tolerate daytime temperatures up to 90 degrees F. and, though warm nights are a pleasure for people, these begonias prefer evenings to be cool, around 55 to 60 degrees F. The third requirement, at least 69 percent humidity, is probably the easiest to meet.

Even if all three conditions don't occur naturally, a few growers' tricks can accommodate these demands. Where the temperature exceeds 95 degrees F., for example, an experienced grower will grow them in full shade under large shrubs such as camellias or rhododendrons, and mist all nearby foliage to lower the temperature and increase humidity.

Ben Herman of Tucson, Arizona, grows his plants in a greenhouse equipped with an evaporative cooler. "When I first tried tuberous begonias, they lasted maybe a week in my climate," he recalls. "That intrigued me. I'm always looking for a challenge!" Herman, professor of environmental physics at the University of Arizona, also compensates for his desert climate by ordering his tubers for delivery in late fall; he then sprouts them in November and enjoys four months of bloom, from late February to early June. This is the direct opposite of what most growers do.

Typically, in nondesert, temperate sections of the country, growers start tubers indoors as early as February and transplant them into pots or beds about two months later to bloom from mid-June until frost.

Even in San Francisco, where the cool, foggy summers are ideal for tuberous begonias, problems can arise. Longtime San Franciscans Alice and Isadore Gold have raised blue-ribbon tuberous begonias for several decades. "We have to give them a little attention because an extreme change from day temperature to night temperature can bring on powdery mildew," Isadore Gold acknowledges. But the Golds suggest spraying an appropriate fungicide to combat this common malady that disfigures begonias.

Several degrees' latitude to the north, the world-famous Butchart Gardens, on Vancouver Island in British Columbia, shares the Golds' experience of cold summer nights after warm days. The staff grows 16,000 plants a year from seed. Throughout the gardens, these begonias show their versatility, growing just the way they do in less-renowned gardens: in beds, various-sized containers, and hanging baskets.

Butchart Gardens mostly grows 'Non-stop' begonias in the beds because they tolerate heat and sun better. It uses the other, showier kinds in containers and baskets. ('Non-stop' begonias, which grow closer to the ground and have smaller flowers than most tuberous begonias, are descended from B. hiemalis.)

Steve Frowine grows tuberous begonias in containers rather than in beds because "You can create a habitat for them more easily," avoiding heavy soils and hot exposures.

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