The PhD degree represents the ability to conduct original research and scholarly work independently at the highest level with minimal supervision. The educational program focuses on developing research skills to become an independent principal investigator.

Advisory Committee

The advisory committee is made up of a minimum of four members of the Graduate Faculty. At least one member must be from outside the department. The advisory committee must be chosen during the student’s first semester in residence. The major professor will serve as chair of the advisory committee. Students and their major professors share joint responsibility to set up and hold meetings of the student’s advisory committee at least once each year.

The advisory committee will assist the student in formulating a program of study, review the student’s dissertation research proposal, and make suggestions concerning the course of graduate study. The advisory committee will have the responsibility of developing and implementing a preliminary examination (see below). The advisory committee will also conduct a final oral examination that may include a defense of the dissertation, an interpretation of other scholarly activities, and a testing of the student’s understanding of their field of study.

The student should consider her/his major professor as the first source for policy information, advisory guidance and access to resources of the Department and University needed to complete all requirements for graduation.

Program of Study

The PhD requires at least three years of full-time study beyond the bachelor's degree, equivalent to at least 90 semester hours of graduate course work and research credits. Up to 30 hours of graduate credits at the MS level may be applied toward the PhD program of study; the courses that can be applied should be relevant to the current PhD program. The PhD degree requires a dissertation representing at least 30 hours of research credit.

Thus, beyond a master's degree from which 30 credit hours are applied towards a PhD, course and curriculum requirements are as follows:

  • 60 semester hours of course work and research credit, to include:
    • 24 to 30 credit hours of graduate course work
      • Must include 3 credit hours of Graduate Seminar (HORT 951)
    • 30 to 36 credit hours of research (HORT 999)

The program of study will be developed initially through consultation between the major professor and the student. Courses to be taken should fit into a unified plan aimed at providing the student with a comprehensive background in the chosen area of interest. Initiative in program design by the student is encouraged. The program should be presented at the initial meeting with the Advisory Committee. The program of study form is available from the Graduate School.

Doctoral students should earn a significant majority of their course work credit hours that are required by their programs of study in courses numbered 800 or higher. Although supervisory committees have considerable latitude in providing an appropriate program of study for their students, they are encouraged to follow these guidelines:

  1. Of the 24 to 30 hours of course work credit hours beyond the master's degree approved by the supervisory committee, 15 credit hours should be at the 800-level or above, in addition to doctoral research credit hours.
  2. For course work beyond the master's degree, no more than 6 credit hours of 500-level courses are permitted in a doctoral program. No 500-level course taken in the student's major field of study, e.g., Department, may appear in the program of study.
  3. Not more than 6 hours of problems or other individualized courses should ordinarily appear on the program of study for the doctoral program.
  4. For students who bypass the master’s degree, the program of study must include at least 15 credit hours at the 800-level or above, in addition to doctoral research credit hours. No more than 12 credit hours of 500 level courses are permitted in a doctoral program and they must come from outside the student’s major field of study (e.g., Department).

Upon approval by the major professor and advisory committee, the student will submit their program of study to the Graduate School. The program of study must be approved and submitted to the Graduate School prior to the end of the student’s second semester (excluding summer semester). All changes in the program of study must be approved by the advisory committee, Graduate Program Director or Department Head, and Graduate School.

Graduate Research

All PhD students must conduct original research, under the supervision of the major professor and the advisory committee, on a selected problem related to their field of study. A research proposal must be developed as the first step in the research process. The research proposal should demonstrate a sufficient level of understanding of the researchable problem, the appropriate methodology, and scientific rationale to be approved by the student's advisory committee. The experimental data collected must be analyzed, interpreted, and presented in the form of a bound dissertation.

The research proposal should be presented to the advisory committee for their approval and recommendations prior to the end of the student's second semester (excluding summer semester).

A baseline expectation for all students is that they develop a brief research proposal that addresses each of the following elements pertinent to developing scientific research skills:

  1. one or more testable hypotheses
  2. clear research objectives
  3. rationale for the proposed research, including a scientific literature review and, if available, preliminary data
  4. feasible proposed research methodology
  5. expected outcomes
  6. potential impact
  7. pertinent literature citations

The process of developing a concise research proposal is an appropriate and necessary prerequisite for the eventual completion of the research thesis. As a general rule, the proposed research effort should be rigorous and of high enough standard to merit its publication in a peer reviewed journal.

Teaching Experience

All PhD students, regardless of funding source, must participate in the teaching program of the Department of Horticulture and Natural Resources for one semester during their degree program. This requirement cannot be waived. The purpose of this requirement is to ensure that all PhD students have a personal experience with instruction as a chance to develop teaching and communications skills. It is important that the assignment be meaningful and equivalent to what is expected of a half-time teaching assistant (10 to 20 hours per week); only conducting grading and clerical activities do not meet the spirit of this requirement.

Teaching assignments are made annually by the Director of Graduate Programs and the student's adviser in concert with the Undergraduate Teaching Faculty. Teaching assignments are typically made at the end of the Spring semester for the subsequent academic year. Prior to making the assignments, current students will be asked to provide a list of courses with which they would like to assist, if possible. New graduate students are typically not asked to serve as a teaching assistant their first semester, but may be asked to assist in their second semester.

Outreach / Extension Experience

An outreach experience gives students exposure to a potential area of employment, adds to their expertise in their field of study, and helps them gain empathy for the industry and public that the discipline serves. Each student must participate in two of the three general categories listed below. Major advisers should arrange for these experiences, and the activities are ideally decided on at the time of filing the Program of Study. After completion of the extension experience, the activities conducted must be briefly described and documented by the student in their Annual Progress Report.

I. Developing and Communicating Information

  1. Present research-generated information in a form and in a medium designed to reach either the general public or industry.
  2. Prepare and present a talk on a horticultural, park management and conservation, or wildlife and outdoor enterprise management topic to an audience of non-scientists; examples include garden clubs, commodity groups, and extension meetings.
  3. Use an alternative or creative medium to deliver information; examples are websites, television or radio, on-farm or other demonstrations, or materials delivered electronically.

II. Interacting with the Public

  1. Assist in developing and conducting a commodity or other meeting designed to attract a large and diverse audience. Assisting with only clerical or audiovisual equipment duties does not fulfill the spirit of this requirement.
  2. Participate in the planning and execution of a tour. This could involve a facility tour or it could involve scheduling visits for a group of professional, including international groups.
  3. Travel with an extension specialist on assignment for at least three days, which need not be consecutive.
  4. Assist in responding to requests for horticultural or natural resources information from extension agents.

III. Public Service

  1. Presenting programs or developing materials for public or private schools, including preschools, in your field of study.
  2. Presenting programs or developing materials for other educational institutions or groups, in your field of study.

The student may undertake an extension activity not described herein subject to approval by his/her major adviser and the Director of Graduate Programs. Waiver of this experience must be requested at the time that the Plan of Study is submitted, and it will only be approved for students with extensive backgrounds in extension. Waiver requests submitted near the completion of a student's degree will not be considered. Students who pursue both the MS and PhD degrees in our Department are only required to fulfill this requirement during their MS program.


Preliminary Examination

A comprehensive knowledge of the student's major and related fields must be demonstrated to the advisory committee by written and oral examination at least seven months before the final oral examination. Students must take the initiative to schedule the written preliminary exam with each member of the advisory committee, and the schedule should be submitted to the Graduate School one month before the scheduled exams. One month is allowed for the preliminary examination period. The written preliminary examination may be followed by an oral preliminary exam at the discretion of the advisory committee. The preliminary examination must be completed successfully for the student to be advanced to candidacy for the doctoral degree and therefore eligible to schedule their dissertation defense. Students must be registered during the semester(s) in which they take the preliminary examination. All portions of the examination must be passed before a student is granted the candidacy. Upon the successful completion of the preliminary examination, the Graduate School will appoint an outside chairperson to the advisory committee who will preside over the thesis defense and final oral examination. A failed examination may be retaken once without permission from the Graduate Council, but the failed examination should be reported to the Graduate School. The student will be notified of their acceptance as a candidate for the PhD Degree by the Graduate School. After successful completion of preliminary examination, the period of candidacy will last up to five years. After five years have lapsed, the preliminary examination must be retaken. Students earning the candidacy should be continuously enrolled until the completion of the degree.


Doctoral Dissertation

The Doctoral dissertation is based on original research conducted in partial fulfillment of requirements for the PhD degree and is prepared under the supervision of the major professor. It must be approved by the advisory committee. The dissertation may be written either in journal paper format, with each chapter prepared as an independent manuscript (strongly recommended), or in the “classical” chronological style.

A copy of a draft of the dissertation that has been reviewed and approved by the major professor is given to each member of the advisory committee at least two weeks prior to the dissertation defense date (final oral examination, see below).


Final Oral Examination (Dissertation Defense)

Prior to scheduling the final oral examination, all changes to the student’s program of study must be approved and any incomplete or deferred grades (except HORT 898 or 899) resolved. Students must be registered for at least one (1) credit hour during the semester of the final oral examination.

A dissertation defense seminar based on the student’s dissertation research or project report will precede the oral examination. The defense seminar is open to public, while the final oral examination, which follows the thesis defense seminar, is limited to the advisory committee including the outside chairperson. Notice of the seminar and final examination should be done at least one week prior to the examination. The dissertation and the student’s performance on the final oral examination must be approved by three-fourths of the committee members to pass. A failed examination may be retaken with the permission of three-fourths of the advisory committee and may not be scheduled until at least 3 months have elapsed. Upon successful completion of the final examination, the student shall submit an electronic copy of the approved dissertation to the Graduate School before the set deadlines.

The Dean of the Graduate School will appoint a member of the graduate faculty to serve as chairperson of the final oral examination. This individual has responsibility to read the dissertation, to make recommendations, and to be sure that the dissertation is in acceptable form. In addition to presiding at the final oral examination and evaluating the examination as a test of the student’s ability to be awarded the PhD degree, the chairperson also votes on the candidate’s performance.