College of Knowledge: Greenhouse & Horticultural Lighting

Course Overview

This 4-hour class consists of pre-recorded lectures and video demonstrations that are divided into seven units and includes the importance of light for plant growth; light quality, intensity, and quantity; photoperiodic lighting; and photosynthetic (high-intensity) lighting with both conventional lamps and light-emitting diodes (LEDs). Participants will learn about the properties of light, how light regulates extension growth and flowering, how to measure the properties of light, and how to apply these concepts to a range of specialty crops including those grown in greenhouses and completely indoors. It provides introductory to moderately-challenging content based on experiments performed at Michigan State and Purdue Universities.

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 recent trade articles published on pertinent lighting topics.

The course is instructed by Heidi Lindberg, Greenhouse and Nursery Extension Educator with MSU 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 (Assistant Professor, MSU) and Dr. Garrett Owen (Outreach Specialist, MSU).

Course Content

The 4-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.

PreviewView a preview of the course here.

Cost: The cost is $129 per person.

Course Offerings: This course is offered once a year in the winter months.

    • Registration period: November
    • Course available to students: December-February

Win a $75 gift card! The individuals have paid for the course, completed the pre-test, final exam, and the post-course evaluation, will be entered into a raffle for a $75 gift card! (Available to U.S. residents only)

Financial Need Scholarships: There are three 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. Scholarship winners will be notified after the enrollment period has passed.


Registration for the Winter 23-24 Courses is now closed. This course will be open for registration again on November 1, 2024. To be added to a waitlist to be notified when it opens, take thissurvey. 

Frequently Asked Questions

What is my username/NETID?

Your username (or NET ID) is the email address you used to create your account during registration (you use the same email address/password for registering and for taking the course).

What URL do I go to for logging into the course?

Go to: You will see the Michigan State University at the top of the page. Login with the email address and password you set during the registration process.

I received a “not authenticated” response when trying to login – what do I do?

A “not authenticated” message is typically an issue with a password not being entered correctly.

I forgot my password – where can I reset it?

If you need to reset your password at any time go to and select the option for "Need help Signing in.