[MPWG] Program Points to Pleasing Plants

[Sonya]

Source: University of Arkansas, Fayetteville Released: Thu 10-Feb-2005, 
12:00 ET
Program Points to Pleasing Plants

Some plants can’t be left out in the cold, but an ongoing experiment 
examines underused deciduous and evergreen shrubs and trees to see which 
ones can. Plants that prove themselves offer landscaping alternatives in 
three USDA cold hardiness zones found at various locations throughout 
the United States.


Newswise — Some plants can’t be left out in the cold, but an ongoing 
experiment by University of Arkansas researchers examines underused 
deciduous and evergreen shrubs and trees to see which ones can.. Plants 
that prove themselves offer landscaping alternatives in three USDA cold 
hardiness zones found at various locations throughout the United States.

In 2004, Jon T. Lindstrom, associate professor of horticulture, and Jim 
Robbins, extension specialist with the University of Arkansas Division 
of Agriculture, evaluated the first “graduating class” of plants that 
they placed in the ground in 1999. The researchers developed plant 
testing sites in Fayetteville, Little Rock and Hope, which represent 
three different cold-hardiness zones within the state and across the 
nation.

The program has several goals, including evaluating ornamental plants 
that can be used as screens or hedges in a garden landscape, evaluating 
the cold hardiness of broadleaf evergreens, and evaluating plants rarely 
seen in Arkansas nurseries or landscapes. These plants may be new to the 
commercial market, or may be common in other states with similar 
cold-hardiness zones but not common here, Robbins said.

The researchers get the plants from commercial nurseries that want to 
“test drive” new plants, or they propagate the plants themselves. They 
have received plants from nurseries all over the country and Canada, 
including Michigan, Iowa, Oregon, Washington, Georgia, South Carolina, 
New Jersey, Oklahoma, Louisiana, British Columbia and Texas.

They have tested plants from azaleas to viburnums, with lots of holly, 
crape myrtles and oaks thrown in for good measure. Every year since 
1999, they have planted an average of 15 new plant varieties at the 
three sites.

“We’re generating information that should be of interest to the nursery 
industry,” said Robbins. Landscapers and nursery companies constantly 
seek different plants to offer variety to gardeners, but often lack data 
to know whether novel plant types will live and die in a given hardiness 
zone.

The plant evaluation program can assist nurseries because it evaluates 
several plants of the same variety at multiple sites over multiple 
years. It’s one of the most comprehensive evaluation programs at a 
university, Robbins said. The quantitative data will give nurseries 
vital information they need to make decisions about which plant 
varieties to stock and sell.

“You never know what the weather is going to be like, over time, in just 
one year,” Lindstrom said. In a given year, “you may get that test 
summer or test winter, or a drought, and then you can see if the plants 
will make it through.”

As the program has continued through the years, some of the plants 
proved intolerant to the colder climate in Fayetteville, making them 
undesirable for growing in this part of the state. Some of the plants, 
like the Loropetalum chinense, or Chinese fringe flower, stayed alive in 
Fayetteville, but did not flower in the spring. Others, like the dwarf 
crape myrtles, died back in Fayetteville and did not attain their 
expected height.

However, the researchers did find plants that grew well in all the 
zones, like the Dixie Dream™ holly. Another plant that grew well at all 
three sites, Itea virginica, also known as Henry’s garnet, sported 
flowers in May and rich maroon-colored leaves in November and easily 
propagates through cuttings.

Some plants did not live up to the expectations of the researchers.

“There were plants we didn’t like regardless of site,” said Lindstrom, 
recalling one plant that had variegated leaves that returned with new 
growth that had solid-colored leaves. Another plant had no improvements 
to recommend it over already existing, easy-to-find varieties.

The researchers have devised an evaluation scale to help nurseries make 
decisions about which of these underused plants might appeal to 
customers in the different cold hardiness zones.

The plant evaluation program continues to grow, and plants will be 
evaluated as the shrubs and trees planted in 2000 through 2004 reach 
their fifth year. The researchers continue to look for little-known, 
unusual plants to test. This year, they plan to plant a reportedly 
frost-tolerant eucalyptus tree.

They have begun to disseminate the information they have accumulated 
since 1999 through reports that are available on the Web. For 
information on the plant evaluation program, please see 
http://www.uark.edu/campus-resources/cotinus/arboretum_html/planteval.html.

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