Greenhouses and growth chambers

Understanding Plant Health and Light Management Starts with Accurate Measurements

Why measure light and plant stress?

Measuring light and plant stress can influence desired plant characteristics—including growth rate, chemical composition, taste, and nutrition.

LI-250Q PAR Package

Portable greenhouse and growth chamber light measurement system

Light management is a critical factor in commercial greenhouse and growth chamber efficiency. Choose the LI-250Q package for spot measurements of photosynthetically active radiation (PAR) intensity and quantity with unrivaled accuracy.

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Measure the light that matters, no matter the source

Plant growth is driven by PAR, which occurs at wavelengths between 400 and 700 nm. Not all light contains PAR, and PAR requirements vary between types and growth stages of plants.

The LI-190R Quantum Sensor, included in the LI-250Q package, provides uniform sensitivity across the entire PAR waveband, delivering the most accurate PAR measurements of any sensor on the market.

The LI-190R Quantum Sensor measures PAR inside greenhouses and growth chambers with the same precision from the sun, artificial lighting, or both without the need for calibration or correction factors. Compatible artificial sources include incandescent and high-pressure sodium lamps, high-intensity fluorescent lights, and the rapidly emerging range of LED light systems.

Why take instantaneous PAR measurements?

The LI-250Q package allows you to capture the instantaneous flux of photons (µmol m-2 s-1) with wavelengths in the PAR range to assess whether your plants are getting enough light at any one point in time. This assessment depends on your unique lighting requirements and can be used to make informed light management decisions, including:

  • Plant placement and spacing
  • Types of supplemental lighting
  • Distance of supplemental lighting from plants
LI-190R quantum response energy LI-190R quantum response photon
LI-190R response vs. ideal quantum response in energy units (top) and photon units (bottom).

LI-1500 DLI Package

Automatic capture and calculation of Daily Light Integral

Expand your light measurement capabilities with data logging, long-term measurements, continuous PAR measurement, and automated calculation of Daily Light Integral (DLI) with the LI-1500 DLI Package.

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DLI graph
DLI is a measure of the total amount of light received in a single day in a particular area. DLI is calculated as the time integral of the series of instantaneous PPFD readings (Qi) taken at regular intervals (Δti).

Why measure DLI?

An important lighting consideration is the total amount of light your plants receive daily, which cannot be easily extrapolated from instantaneous measurements. One of the most common ways of calculating total daily light is DLI, which reports a total number of moles (instead of micromoles) of photons per day (instead of per second).

Maintaining a consistent DLI based on your plant type and growth stage is critical for achieving ideal growth and maximum yield. However, the amount of supplemental lighting required to maintain a consistent DLI can vary dramatically throughout the year. Providing too little light may negatively impact growth and production, while providing too much light may also negatively impact growth while wasting costly energy resources. With the LI-1500 DLI package, you can ensure that you provide the correct light amount to optimize greenhouse production while conserving resources and being mindful of your bottom line.

Simplify DLI calculation with the LI-1500 DLI Package

Accurate DLI measurements require that measurements are taken at precise, regular intervals and use complex calculus to find the integral of the intensity-time curve. The LI-1500 DLI package greatly simplifies this process, automatically capturing data at the correct intervals and doing the math for you.

After programming your LI-1500 based on your light sensor’s calibration information, calculating DLI takes three simple steps:

  1. Deploy in your greenhouse. The LI-1500 and LI-190R are rugged and well suited for long-term deployment in hot and humid greenhouses.
  2. Let the LI-1500 log data over your measurement period. The LI-1500 can log data for a short, 8-hour winter day to several days or weeks at a time.
  3. Download your data file. The LI-1500 automatically calculates DLI and reports it in a comprehensive format that shows how DLI changes at each measurement.

LI-193SA Spherical Quantum Sensor

Measure light in the entire room

Because plants use light from all directions, it’s useful to measure reflectance from the surfaces in your greenhouse, grow rooms, and chambers.

Why measure light from all directions?

Originally designed as an underwater sensor, the LI-193SA Spherical Quantum Sensor also measures light in the air, providing insights on how to maximize the efficiency of your grow lights and reflective surfaces. Its compact size makes it easy to map light intensity and its impact on your grow in all areas of your space, including within canopies to map light reaching lower leaves. Use the LI-193SA with the LI-250A Light Meter and the 2222UWB-3 cable to capture PAR from a near 360° range.

Angular response graph of the LI-193 Spherical Quantum Sensor

LI-180 Spectrometer

A complete spectral profile of supplemental lighting

Take precise, handheld spectral measurements with a polished and powerful interface ideal for the greenhouse grower on the move. Instant, one-click data capture provides actionable results in seconds.

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Why measure spectra?

Not all light affects plant growth and reproduction the same way. Modifying the intensity of specific light bands can influence desired plant characteristics—including growth rate, chemical composition, taste, and nutrition.

The LI-180 Spectrometer allows you to record and optimize the spectral composition of your supplemental lighting, which can add significant value to your greenhouse or growth chamber operation.


Shorten Production Time


Improve Yield Quality

disease resistant

Enhance Disease Resistance

Instant insights

Measure real-time changes from spectral manipulation, height adjustment, and plant positioning. In one click, the LI-180 records dozens of variables—such as PAR (as color-specific photosynthetic photon flux density (PPFD)), photon flux density (PFD), and irradiance (W/m2). Select a measurement to view details, such as ratios of red to blue or red to far-red intensity.

LI-180 screens

Actionable results

Compare the spectra of your lighting to one of multiple reference spectra. Reference spectra are based on pigments that are important for photosynthesis and morphology, such as chlorophyll a or beta carotene. Then adjust your lighting strategy to better match the pigment peaks for species-specific responses throughout your greenhouse. View a variety of tabular and graphical outputs immediately after capture and create custom views and ratios to see your variables of interest.


Flexible software

In addition to the lightweight and portable design, the LI-180 mobile application provides excellent flexibility. Connect any Wi-Fi enabled device to quickly transfer data or customize your display by choosing variables of interest to you. Desktop software enables in-depth analysis, continuous or timed capture configuration, and file management capabilities.

LI-180 ddesktop software

LI-600 Porometer/ Fluorometer

High Throughput Measurements for Expedited Plant Screening

Proper management and understanding of plant physiological stress at different points in the growth cycle can lead to desired characteristics. The LI-600 Porometer/Fluorometer takes high-throughput stomatal conductance and chlorophyll a fluorescence measurements in seconds. Quickly survey greenhouse plants, using its barcode scanner to easily track and organize measurement data from rows or specific plants.

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Why measure plant stress?

Stomatal conductance and chlorophyll a fluorescence measurements can serve as an indicator of a plant’s genetic makeup and its physiological response to greenhouse conditions. Both measurements can help identify stressors and contribute to a more complete picture of a plant’s health.

Greenhouse Publications

Measuring Massive Quantities of Plants
Horticulturist Jake Emling used the LI-600 to measure entire greenhouses of tomato, lettuce, and Cannabis species.

Growing research, responsibility, and relationships at Michigan State
Dr. Roberto Lopez and his lab discuss making discoveries and using science to connect with others.

Must-have meters
LI-COR greenhouse light measurement products were recently featured in a GrowerTalks cover story.

Grow confidently with LI-COR, today and tomorrow

Built upon 45+ years of light measurement experience, other LI-COR instruments for greenhouse and growth chamber research and commercial production include:

LI-830 CO2 and LI-850 CO2/H2O Gas Analyzers

LI-830 CO2 and LI-850 CO2/H2O Gas Analyzers

Precise, stable infrared gas analyzers ideal for greenhouse monitoring.

LI-3000C Portable Leaf Area Meter

LI-3000C Portable Leaf Area Meter

Nondestructive measurement and logging device for leaf area.

LI-6800 Portable Photosynthesis System

LI-6800 Portable Photosynthesis System

Precision gas exchange and chlorophyll fluorescence measurements with the most advanced photosynthesis instrument available.

LI-3100C Area Meter

LI-3100C Area Meter

Efficient, high-throughput area measurements with user-selectable area resolution.

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