Over Twenty Years of Blooming Success

Experimental garden proves which flowering plants will thrive

Gardening in Colorado can be a real challenge. The region's high altitude, intense light, clay soils, and aridity cause problems that multiply when bizarre weather events, such as summer hailstorms, occur. A typical June may bring temperatures ranging from 34 to 97 degrees and less than an inch of moisture. It's enough to try the patience of even the most dedicated grower.

Enter landscape horticulture Professor Jim Klett and his ongoing research into landscape plants for the Rocky Mountain/High Plains region. Klett evaluates annuals, herbaceous perennials, and woody plants and the best ways to grow them. Then he lets growers and retailers know which plants have proven successful.

A large part of his work is managing Colorado State's Annual Trial Garden, an outdoor laboratory that tests more than 1, 100 annual varieties each year.

"Several of the major seed companies have breeders who want to see how the new plants they're breeding will do in our climate," explains Klett. "We have high light intensity and low humidity, but we don't get a lot of the disease and insect problems you often see in Pennsylvania, Michigan, or Georgia, where some of the other big trials are set."

Klett cooperates with about 25 different companies that provide seeds and cuttings for testing, some coming from as far as Costa Rica and Israel. Each March, Klett begins receiving vegetative varieties, which then are grown in the University's greenhouse until late May. The seed varieties come as an in-kind donation. Partners at Denver's Welby Gardens germinate the seed varieties and then supply the seedlings to the University for planting in the outdoor beds.

The trial garden is an official All-American Selection test garden, which tests new seed plants next to one or two comparison varieties. If the new plant proves exceptional, plant breeders will spend several years producing seed so the plant can be introduced to the public. "The test gardens are a way for plant breeders to get useful information about how a new variety will grow in lots of different settings," says Klett. .

In early August, a 30 to 35 member team, comprised of greenhouse growers, faculty, students, public horticulturists, seed company representatives, and Master Gardeners, spends a day evaluating the varieties. They evaluate three different things, says Klett:"the plant, the flower, and an overall evaluation, plus additional comments. " Students then input that information into a database, so that "best-of" varieties can be identified. Those and other results are published in the Annual Trial Garden Performance Report .

"This is what the growers really like, because they can go through the report before the next growing season and see what looks good, then decide what seeds and cuttings to order," says Klett. . The report tells when each variety was planted and provides other cultural information so growers can replicate an ideal growth environment. All green-industry personnel also receive the information after the growing season is over, and consumers learn about the "best-of" varieties at planting time through articles published in Colorado newspapers and magazines.

The Annual Trial Garden began at Colorado State in the late 1970s, when 250 varieties were tested. Today it's recognized as one of the country's leading annual trial gardens. This is Klett's 11th year running the garden, and each year brings something new. Now most varieties arrive as cuttings rather than as seeds. "Some plants are difficult to grow from seed, and it's easier and quicker to grow them from cuttings," says Klett. .

Sometimes the results can be surprising, as in the case of New Guinea impatiens. "People didn't think they would do well in Colorado, because of our high light intensity," Klett explains. . "But we grew them under about 60 to 70 percent shade cloth, and they've been just beautiful all year round. Now, as a result of these trials, we're seeing more and more New Guinea impatiens being sold throughout this whole region. "

Testing new varieties allows companies to diversify and provide an increasingly sophisticated gardening public with more of the unusual things they're demanding, Klett adds. Perhaps gardeners will be intrigued with the 2001 Best of Show, "Magical Michael", a fragrant, purple basil plant boasting lavender-white flowers.

Klett views the flowering outdoor laboratory as a statewide garden – a resource and a showplace not only for the University, but for the community and the green -industry as well.