Light Management in Controlled Environments

Electric lighting is used in greenhouses to regulate the photoperiod to control flowering, or to increase growth to increase crop quality and yield.  It is also used for sole-source lighting of plants grown indoors. A few books and summary articles are below, followed by more in-depth articles on specific topics.

  • Light Management in Controlled Environments, a book edited by Roberto Lopez and Erik Runkle, contains 18 chapters written by 20 leading plant scientists about how light influences plant growth and development of specialty crops grown in greenhouses and controlled-environment growth rooms.
  • LED Lighting for Urban Agriculture, a book edited by Toyoki Kozai, Kazuhiro Fujiwara, and Erik Runkle that focuses on light-emitting diode (LED) lighting for the commercial production of horticultural crops in plant factories and greenhouses. It contains 32 chapters written by plant scientists and engineers in Asia and the U.S.
  • Use of Lighting to Accelerate Crop Timing by Erik Runkle and Matthew Blanchard, Michigan State University.
  • Greenhouse Glazing by A.J. Both, Rutgers University.

Resources

  • Light spectrum for different applications

    Published on September 8, 2021
    This article discusses the effects of the light spectrum on plants, and conceptually how it can be used for different greenhouse and indoor crop production applications.

  • Increasing the daily light integral

    Published on August 6, 2021
    The daily light integral (DLI) refers to the cumulative amount of light received per day, which influences the quality and yield of horticultural crops. This article discusses ways to increase the DLI for plants grown in greenhouses.

  • LEDs: More than μmol×J–1

    Published on July 7, 2021
    Light-emitting diodes (LEDs) are known for their efficiency at converting electricity into light. While efficacy is a very important consideration, there is more to them than just their μmol×J–1.

  • The indoor lighting guide: Growing seedlings under LEDs

    Published on July 1, 2021
    This 24-page guide provides research-based information about producing young plants indoors (without sunlight) under LEDs. Developed in partnership with GrowerTalks magazine.

  • Light fixtures and their photon fluxes

    Published on May 6, 2021
    LED fixture come in all shapes, sizes and outputs — more technically, photon fluxes and spectra. This article explains the photon flux emitted by a light fixture and why it is important.

  • “Hidden” benefits of supplemental lighting

    Published on April 7, 2021
    High light can at least partly decrease the effects of other environmental parameters on greenhouse crops. These can be considered “hidden” benefits because the effects are often not obvious.

  • Sole-source (lighting) for seed

    Published on April 5, 2021
    By producing plants indoors under sole-source lighting, not only can we control plant traits by manipulating the light quality and/or quantity. but we can potentially produce more resilient plants.

  • Maximizing photosynthesis, minimizing respiration

    Published on March 8, 2021
    Conceptually, anything growers can do to increase photosynthesis and decrease respiration can increase growth, leading to thicker stems, faster rooting, more branches, and more and larger flowers and fruits

  • Making sense of light sensors

    Published on February 10, 2021
    In this article, we discuss light sensors, light units, and how to convert light units from a greenhouse environmental control computer into more meaningful values.

  • Early scaling-up challenges with LED lighting

    Published on December 14, 2020
    The fundamental advantages of light-emitting diode (LED) lighting are clear, but it is still a relatively new technology and unfortunately, one can be reminded of that when the jump is made to replace conventional lighting fixtures with LEDs.

  • Effective long-day lighting fixtures

    Published on November 9, 2020
    A large number of ornamental crops flower earlier when grown under long days. This article describes the major considerations when selecting a photoperiodic lighting system to regulate flowering.

  • How Adding Far - Red Radiation to Supplemental Lighting Affects Plugs

    Published on August 13, 2020
    The majority of LED supplemental lighting fixtures on the market provide either a mixture of blue and red radiation with or without green radiation (white LEDs). This can potentially affect subsequent flowering of long - day plants.

  • Red and Blue Radiation: Explore the Efficacy of LED Supplemental Lighting for High-Wire Vegetable Transplants

    Published on August 10, 2020
    High-quality vegetable transplants for high-wire production require a minimum DLI of 13 mol or greater. Therefore, supplemental lighting is commonly used to increase the DLI during light limited times of the year. Can LEDs be utilized?

  • Indoor propagation

    Published on July 14, 2020
    High-value crops can be propagated indoors, inside refrigerated growth rooms and without sunlight. This article briefly lists some of the important considerations for an indoor propagation facility.

  • UV-transmitting greenhouse glazing

    Published on June 16, 2020
    Most greenhouse glazing plastics absorb UV radiation to enhance their longevity. However, plants grown under glazing that transmits UV are typically more compact, darker in color, and more resilient.

  • Common plant production acronyms

    Published on May 8, 2020
    This article briefly defines 20 acronyms (abbreviations formed from the initial letters of other words) commonly used when discussing controlled-environment production of plants.

  • What is the ideal lighting spectrum?

    Published on March 16, 2020
    With LEDs, we can tailor the light spectrum to elicit specific growth responses. This article discusses some of the considerations to identify an “ideal” plant lighting spectrum. As you will read, it’s highly situational.

  • LED fixture efficacy: A 2020 update

    Published on January 13, 2020
    As we enter 2020, there are already more than 50 LED products on the Design Light Consortium's Horticultural Lighting list of qualified products. The spectrum, amount of emitted light, and efficacy vary widely among fixtures.

  • How much supplemental lighting do you need?

    Published on December 17, 2019
    Several factors need to be considered when choosing a supplemental lighting system, and arguably the most important one is to determine what light intensity you want to deliver. This article provides steps on how to do that.

  • Forcing Long-Day Perennials into Flower with High-Intensity LEDs

    Published on October 3, 2019
    Providing long-day perennial plants with supplemental lighting containing greater than 15 μmol∙m–2∙s–1 of blue light is as effective at inducing flowering as low-intensity day extension lighting and supplemental lighting from HPS lamps.

  • Including far red in an LED lighting spectrum

    Published on September 9, 2019
    Growers sometimes wonder whether it is beneficial to include far-red radiation in a light-emitting diode (LED) spectrum. Not surprisingly, it depends on the application and crop.

  • Managing light pollution

    Published on August 9, 2019
    While electric lighting is increasingly used in greenhouses to increase plant growth, yield, and quality, it can have unintended consequences to neighboring areas at night.

  • An overview of long-day lighting

    Published on July 17, 2019
    There are a lot of factors to consider for effective and efficient long-day lighting. This article provides a brief overview of when and how to deliver lighting to create long days inside greenhouses.

  • Is green light useful to plants?

    Published on June 17, 2019
    There is some confusion about the efficacy of green light at promoting photosynthesis. This article explains why and how green light is useful to plants.

  • The economics of lighting young plants indoors

    Published on June 12, 2019
    This article provides the framework of the economics of indoor lighting of young plants (transplants). It includes example costs for an indoor plant factory in Japan, and provides highlights for indoor lighting used by two commercial growers in the U.S.