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Michigan State University Extension is now offering a winter term of the non-credit pre-recorded online course on greenhouse and horticultural lighting. It is the second course in the College of Knowledge Online series offered on the eXtension campus, the national Extension website. The course is intended for greenhouse and ornamental plant growers and others interested in learning about the fundamental concepts about how plants respond to light quality, quantity, and in duration. It provides introductory to moderately-challenging content based on experiments performed at Michigan State and Purdue Universities.

The 3-hours of pre-recorded lecture and video demonstrations are divided into seven units:

  • Unit 1: What is Light?
  • Unit 2: Importance of Light for Plant Growth   
  • Unit 3: Light Quality
  • Unit 4: Light Intensity         
  • Unit 5: Light Quantity 
  • Unit 6: Photoperiod and Photoperiodic Lighting
  • Unit 7: Low- and High-Intensity Lighting
The first and second units cover the properties of light and its importance for plant growth and development. The third unit discusses how light quality influences stem extension and flowering. The fourth unit of the course teaches students about light intensity and its importance for plant growth. It also covers the factors that affect light availability and how to manipulate and measure light intensity in the greenhouse. Unit four also features four videos that demonstrate how light transmission is affected by the glazing material of a greenhouse, how growers can measure instantaneous light intensity and daily light integral in their greenhouse, and also how to measure light intensity and quality from light-emitting diodes (LEDs). The fifth unit discusses how light quantity affects plant shoot and root growth and branching, focusing on responses to the average daily light integral (DLI). Unit six covers photoperiod and photoperiodic long-day lighting strategies, featuring the latest research on delivering long days with LEDs. The final unit on supplemental lighting discusses the advantages and limitations of different lamp types, provides guidelines of when to deliver supplemental lighting to increase DLI, and the factors to consider when selecting a lamp for your horticultural application.

The course is instructed by Heidi Wollaeger, Greenhouse and Nursery Extension Educator, with Michigan State University Extension. The course was adapted and updated from the original College of Knowledge unit developed by Dr. Royal Heins (Professor Emeritus, MSU) and includes a substantial amount of recent research by Dr. Erik Runkle (Professor of Horticulture, MSU).  Supplemental content including videos demonstrating concepts are from Dr. Roberto Lopez and Garrett Owen (Purdue University).

Students enrolled in this self-paced course will take a pre-test and a final exam to gauge their progress on the topics of the course. Self-assessment quizzes will engage students with the material throughout the course. The course also provides links to 36 trade articles published on pertinent lighting topics.

Greenhouse and Horticultural Lighting is available through

Course offerings: This course is offered twice a year (summer and winter).The next enrollment period will begin on Oct. 7, 2016. Students will have access to the material from December 2016 through February 2017.

Cost: $129* per student
*Once students have paid for the course, completed the pre-test, final exam, and the post-course evaluation they will be eligible for a $20 refund. The students must complete all criteria by Feb. 28, 2017 and have emailed the instructor, Heidi Wollaeger (, by Feb. 28, 2017 to receive the refund. If all conditions are met, the cost of the course is $109.

NEW for Winter 2016: There are four scholarships available for those that are interested in the course but do not currently have the financial means to take it. Greenhouse growers interested in the scholarship will be able to apply for it upon registering by writing a short paragraph about why you feel you should be awarded this scholarship and how you plan to use the information you learn in your business or professional endeavors. The applicants and winners will be kept confidential. The cost of the course will be $39.99 for scholarship winners.

Cancellation policy:
Due to the online nature of this course, students wishing to cancel their registration are subject to a $129 fee.

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Michigan State University is committed to providing equal opportunity for participation in all programs, services and activities. Accommodations for persons with disabilities may be requested by contacting the event contact two weeks prior to the start of the event. Requests received after this date will be honored whenever possible.

Contact Information

For information regarding the course, please contact Heidi Wollaeger at or 269-384-8010.