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Plant Collections and Evaluation Program

The University of Tennessee Gardens, located in Knoxville and Jackson, are part of the UT Institute of Agriculture. Their mission is to foster appreciation, education, and stewardship of plants through garden displays, collections, educational programs, and research trials. An integral research aspect of the Gardens is the Plant Collections and Evaluation Program, which annually evaluates the landscape appeal and performance of approximately 4,000 different herbaceous and woody plants in the Gardens’ mid-South region.

Disciplines / Departments

  • Plant Sciences
  • Entomology
  • Plant Pathology
  • Horticulture

Faculty Members / Participants

  • Sue Hamilton, Ed.D., principal investigator and interim director, UT Gardens
  • Bob Hayes, Ph.D., West Tennessee Research and Education Center
  • James Newburn, M.S., Plant Sciences
  • Jason Reeves, M.S., West Tennessee Research and Education Center
  • Beth Willis, M.S., Plant Sciences

Results / Achievements / Distinctions

  • Earned distinction of Tennessee Certified Arboretum from Tennessee Department of Agriculture, 2003;
  • Earned distinction of Conifer Reference Garden from American Conifer Society, 2008;
  • Earned distinction of American Garden Award Garden by National Garden Bureau, 2008;
  • Invited to join the National Plant Collection Consortium of the American Public Garden Association, 2008;
  • Industry trial sponsorship, approximately $25,000 annually;
  • Two plant evaluation reports, Winter Trials and Summer Trials, are released each year (;
  • Evaluation summations and choice plant selections are published in three commercial trade magazines each year: GMPro, Grower Talks, and Greenhouse Grower.


The Plant Collections and Evaluation Program advances ornamental horticulture by providing unbiased evaluations of landscape plant performance in the mid-South region of the United States in order to enhance the profitability of Tennessee’s green industry. End-users include the gardening public, commercial nursery and greenhouse growers, contracting and management firms providing landscape services, independent garden centers, home improvement centers, mass merchandisers, and chain retail stores.

Research Goals

  • To determine the landscape performance and potential uses of experimental or new ornamental landscape plants and their potential to increase the economic and environmental sustainability of Tennessee’s green industry;
  • To develop and build a variety of plant collections relevant to commercial landscaping for resource and education to support Tennessee’s green industry;
  • To increase awareness of selected outstanding plants from the program among professionals and consumers of Tennessee’s green industry.

Research Procedure

Our research follows industry standards set by commercial seed and propagation companies, as well as procedures used by similar university plant evaluation programs. Between 12 and 36 plants are planted in single evaluation plots. All plants in the plot are evaluated collectively (as a single display unit) from a landscaper’s perspective, using a standard rating. Plants are given this visual rating three times throughout the growing season—at the end of June, July, and August—by the same person or staff members. The three different ratings are averaged, giving each plant an overall landscape performance rating for the growing season. Field notes are recorded throughout the season. All relevant information is included in the summary section for each plant entry in the final report.


The UT Gardens host several commercial and consumer educational events each year to showcase the Plant Collections and Evaluation Program. Summer Celebration and Blooms Days are the two annual community educational events, with more than 8,000 attendees collectively. Numerous educational walks, talks, and school fieldtrips are given throughout the year, with more than 6,000 participants per year.

Outreach / Economic Development

More than 60,000 people visit the UT Gardens each year to view the plant trials and collections. A marketing program, Best & Beautiful Plants from the UT Gardens, heightens consumer and industry awareness and aids in the marketing of outstanding plants selected from the plant collections and evaluation program. Numerous industry trade and consumer periodicals publish the trial results each year. Results are also presented at local, state, and national seminars and symposia to industry professionals and consumers every year.

Contact Information

Sue Hamilton, Principle Investigator
Department of Plant Sciences
Room 252, Ellington Plant Sciences Bldg.
2431 Joe Johnson Drive
Knoxville, TN 37996-4561

Phone: (865) 974-7972

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