What do you want to know about the lighting of plants in plant productions in a controlled environment?

Do you have questions about the optimal light levels for growing environment-controlled crops? What about which grow lights would work best for your crops and production facility? More importantly, do you want to know how much is it going to cost you to run these grow lights?

These questions and many more will be answered in the first Short Course on Plant Lighting. This six-week virtual event is scheduled from October 14 to November 18, 2021.

The short course was developed through a partnership between the Greenhouse Lighting and Systems Engineering (GLASE) consortium, OptimIA and LAMP.

The aim of the short course is to provide participants with the opportunity to learn more about all aspects related to the selection, implementation and benefits of factory lighting systems. The abridged course has been organized into six educational modules which will be presented and moderated by leading industry experts and academic researchers.

Module 1: Introduction to crop lighting

Module 2: Deciding to use crop lighting

Module 3: Plant production with auxiliary lighting

Module 4: Crop lighting systems

Module 5: Economics of crop lighting

Module 6: The future of crop lighting

In addition to educational topics, participants will have the opportunity to learn and use interactive tools that can help define specific lighting requirements, including:

1. Photosynthetically Active Radiation (PAR) light sensors
2. Full Daily Light Map
3. Light uniformity assessment
4. Virtual Grower Decision Support Tool (USDA)
5. Lighting cost calculators
6. Advanced lighting controls (LASSI)

By the end of the short course, participants will have the information and tools to make decisions on the best options to meet their lighting needs. The short course covers all the topics growers need to think about when considering greenhouse lighting.

At the end of each module, there will be a 25-minute question-and-answer period. This will allow several lighting researchers and industry experts to comment on a particular issue. In addition, participants have the option of earning up to 12 Certified Cultural Advisor Continuing Education Unit (CEU) credits.

How much light do CEA cultures need?

During Module 1: Introduction to Crop Lighting on October 14, Neil Mattson, Associate Professor of Horticulture at Cornell University and Principal Investigator at GLASE, will focus on crop lighting needs. He will talk about the most common controlled environment crops including leafy greens, tomatoes, cucumbers, strawberries and hemp.

“I will discuss the amounts of CEA light cultures that perform optimally and produce high quality and yield,†said Mattson. “Some cultures have specific photoperiod requirements. For example, hemp requires a short daylight span to flower, which requires a blackout (i.e., light deprivation curtains) for year round flowering. Tomatoes need a dark period of four to six hours at night. Lettuce, on the other hand, can be lit for 24 hours. The number of hours per day that light can be provided has an impact on the size of a lighting installation. “

“Along with knowing the amount of light for a crop, it’s also important to know how that light is delivered over the course of a day to make sure plants are getting the light they need. I will also be sharing the results of some of our GLASE research studies on how the amount of light affects the productivity of strawberries, lettuce, and tomatoes.

Objectives and lighting differences

Erik Runkle, professor of horticulture at Michigan State University and director of the OptimIA project, will make three presentations during the short course. The aim of the project’s research and extension activities is to help indoor agricultural producers to be more profitable and sustainable.

“Five of OptimIA’s researchers are using lighting in one way or another in their research,†said Runkle. “It doesn’t mean that their research is focused solely on light, but light is somehow involved in their research. For example, they can look at light in combination with other parameters such as the interplay between light and temperature or light means to alleviate lettuce tip scorch.

Runkle’s first presentation in Module 1 on October 14 will discuss how the light environment is manipulated in plant production.

“This will be a high-level discussion of what producers can do to moderate light intensity, such as glazing material and the effect that can have on light transmission,†he said. “This could involve the use of shade screens to modulate the light. Growers should also be aware of items that cause shade, such as overhead obstructions like hanging baskets. In some cases, most of the steps taken to dim light are done for a reason. However, growers can dim the light without even thinking about it and what the impact might be. “

Runkle will also talk about the different types of lighting that can be used in greenhouses. It will mainly focus on low intensity lighting to regulate the photoperiod and high intensity lighting or supplemental lighting to increase growth.

“There is still some confusion from producers about the difference between these two types of lighting,†he said. “Growers may think they can provide low light intensity and see increased plant growth, which usually doesn’t happen. I want to make sure people are clear about the lighting goals and the intensities needed to achieve their goals.

Runkle’s second presentation will take place during Module 3: Plant production with additional lighting on October 28.

“During this module we will cover the basics of photoperiod lighting, why it could be used and how to develop and deliver an efficient lighting system,†he said. “I’m going to discuss photoperiod or low intensity lighting and how to create long days when the days are naturally short. This will focus on different lamps, including conventional lamps such as incandescent bulbs as well as the many LED options that exist today.

“I will also talk about cyclic lighting, which is intermittent lighting during the night, causing the lights to operate on on and off cycles. I will also talk about the spectrum of photoperiod lighting as this could influence the efficiency of the light as well as the intensity.

In its third presentation in Module 4: Crop Lighting Systems on November 4, Runkle will compare high pressure sodium and LED grow lights.

“I will focus on high intensity lighting applications by discussing the pros and cons of both technologies,†he said. “HPS is the conventional luminaire and the proven technology at a lower cost. But it also has a fixed spectrum and is less efficient than LEDs.

“I’ll talk about when a situation might lend itself to HPS and LEDs might be more profitable. It is not a technology better than another. Rather, it’s a question of which device is the most economical for specific applications.

What is the price of artificial lighting?

Marc van Iersel, professor of horticulture at the University of Georgia and member of the LAMP research and extension project, will discuss the lighting cost calculator developed by LAMP members. van Iersel will speak at Module 5: Economics of crop lighting on November 14th.

“Lighting Approaches to Maximize Profits (LAMP) is a USDA funded research and awareness project with the goal of maximizing profits by improving lighting systems used in controlled environment agriculture,” said said van Iersel. “There hasn’t been a lot of research that specifically focuses on the economics, profitability of lighting. LAMP members want to have a real impact on the industry and profitability is more important than anything else.

The Lighting Cost Calculator was developed to help growers estimate the cost of additional lighting in greenhouses.

“The reason for the development of the calculator was that if a greenhouse technician was considering installing or replacing the current lighting system, it is difficult to determine which is the best economical option for the installation,†said van Iersel. “It’s easy to calculate the capital expenditure because different fixture manufacturers can provide quotes on fixtures as well as any discounts that may apply. However, it is difficult to determine what the operating expenses of these lights will be.

“The calculator tool makes it possible to estimate operating expenses for a given production area. The calculator allows producers to look at different scenarios before deciding what type of lighting they want to install. Hopefully the calculator will help them make more informed choices. One of the unique features of the calculator is that growers can enter their zip code and the calculator retrieves typical lighting data for a specific location and can customize operating expenses for that location.

David Kuack is a freelance technical writer in Fort Worth, Texas; dkuack@gmail.com.

Editor’s Note: This article originally appeared on glase.org.