Want a Grow Sensor?
Get early access to the now.

The ultimate PPFD meter to optimise your grow room

Lucy Starley
February 19, 2024
10 min read
A grower using a PPFD meter to optimise their grow room lights.
A grower using a PPFD meter to optimise their grow room lights.
Download your free VPD calculator
Oops! Something went wrong while submitting the form.

When you're keen on indoor gardening or hydroponics, you know that light is the lifeblood of your plants. But not just any light will do. 

To truly thrive, your plants need the right kind of light at the right intensity and for the right duration. That's where a PPFD meter comes into play, becoming indispensable in your gardening toolkit.

A PPFD (Photosynthetic Photon Flux Density) meter doesn't just measure light. It measures the specific light that your plants can use for photosynthesis. 

Whether you're an advanced indoor horticulturist or just starting out, understanding and using a PPFD meter can transform your approach to plant care. It can elevate your grow room or hydroponic garden, making it more efficient and productive. 

Stay tuned as we dive into what makes a PPFD meter an essential device for any serious grower.

Disclaimer: Any information given on this site is for educational purposes only. Please ensure if you’re growing cannabis plants, you’re doing so in accordance with the law and subject to appropriate permissions and licenses of the applicable country.

A grower holding a PPFD meter to optimise their grow room lights.

What is a PPFD Meter?

A PPFD meter for plants measures the Photosynthetic Photon Flux Density. Essentially, it quantifies the amount of light available for photosynthesis. This light is measured in micromoles per square meter per second (µmol/m²/s). 

Understanding the PPFD value is crucial because not all light contributes to plant growth. Only the light within a specific range of the full spectrum is used for photosynthesis. (Mainly in the blue and red wavelengths). 

A PPFD grow light meter for plants zeroes in on this vital range. It helps you to ensure you're not just blasting your plants with light but nurturing them with the right kind of light. 

This makes a PPFD meter an invaluable asset in optimising your lighting to match the specific needs of your plants. Which will lead to healthier growth and increased yields.

An graph showing the impact PPFD has on yield and growth.

What’s the difference between PPFD and PPF

When people talk about plant lighting, two terms frequently pop up: PPFD and PPF. While they might sound similar, they represent different aspects of plant lighting. 

  • PPF or Photosynthetic Photon Flux (PPF) measures the total amount of light produced by a light source per second at a single point. It’s measured in micromoles per second (µmol/s), and describes the light intensity emitted by your grow lights.

An illustration explaining what PPF is and why its helpful to growers.

  • PPFD Photosynthetic Photon Flux Density takes this a step further by measuring how much of that light actually reaches your plants per square meter. It provides a more accurate representation of the light your plants can use for photosynthesis over a larger area. 
An illustration explaining what PPFD is and why its helpful to growers.

This is why a PPFD meter for LED lights, or any grow lights, becomes an essential tool. It helps you understand how powerful your light is and how effective it is in nourishing your plants.

By understanding both PPF and PPFD measurements, you can make more informed decisions about your grow space’s lighting. You can make certain that your plants receive the optimal amount of usable light for healthy growth and development for the size of your grow room.

The grow sensor, which has a top mounted PPDS sensor on. And an image of the Grow  app.

Our revolutionary Grow Sensor with top-mounted PPF meter

The Grow Sensor sensor stands out in the pursuit of precision plant care. Its top-mounted PPF light meter sets a new standard for accuracy in grow room monitoring. 

Placing the Grow Sensor correctly means that you can capture and measure the light intensity directly as it comes from your grow lights, continuously. This ensures that the readings are as accurate as possible. 

This gives you complete confidence in the data you base your decisions on. You’ll know for sure that your plants are receiving the optimal light for their growth, at every stage of growth.

Precision and its ability to integrate seamlessly into your existing setup sets our sensor apart. 

Designed with growers like you in mind, it's easy to install and even easier to use. Providing real-time data that can be the difference between a good harvest and a great one. 

The Grow Sensor’s case design also means that the sensor is unobtrusive. Casting minimal shadows and not interfering with the light distribution makes it the best PPFD meter for growers serious about maximising their plants’ potential.

This innovative approach to measuring PPF means having the most accurate measurements and information at your fingertips. Allowing you to adjust light settings in real time for the best possible plant health and yield.

Get early access to the Grow Sensor

Continuous live PPF readings: Next-level monitoring

The true power of our Grow Sensor lies in its ability to deliver continuous live PPF and PPFD readings. It’s a feature that sets it apart from other grow room monitors. 

This capability allows you to monitor your light environment in real time. So you can make adjustments on the fly to ensure optimal light conditions throughout the day. 

Our sensor keeps you informed every step of the way. This continuous stream of data is more than just numbers on a screen. It's actionable insight that can significantly impact your plants' growth and health. 

The Grow App accompanying the Grow Sensor is also a PPF meter app. The data is presented intuitively and is easy to understand. This empowers novices and the most advanced growers to make informed decisions about lighting setup. 

This technology makes maintaining the perfect light environment less about guesswork and more of a science. You can just sit back and watch your plants thrive under the best possible conditions.

Battery-powered convenience and advanced features

The Grow Sensor sensor is not just another gadget in your grow room; it's a leap forward in plant care technology that promises increased accuracy. 

Being battery-powered, it offers unparalleled convenience and flexibility in where you place it. You can position the sensor exactly where it's needed without worrying about power outlets or messy cables. 

This mobility means that you can also measure accurately whilst getting readings in different parts of your grow space. Giving you the ability to tailor your lighting to the needs of specific plants or areas.

But the innovation doesn't stop with convenience. The sensor also incorporates a spectral radiometer. This feature elevates it from a mere PPFD light meter to a comprehensive plant health tool. 

This advanced component provides detailed insights into the spectrum of light your plants receive, not just the intensity. 

Understanding the spectrum is crucial because different wavelengths play various roles in plant development, from root growth to flowering. 

The dashboard of the Grow Sensor app.

What else can the Grow Sensor do?

The Grow Sensor stands at the forefront of precision and innovation for indoor growers. 

With continuous PPFD monitoring and a full-spectrum quantum PAR sensor, it also boasts an array of additional features:

  • Temperature and humidity monitoring and Vapour Pressure Deficit (VPD) tracking.
  • Built-in CO2 monitoring.
  • Daily Light Integral (DLI) calculation.
  • Leaf Surface Temperature (LST) sensing.
  • Dew point monitoring.
  • Compatibility with the Grow soil probe for measuring EC, soil moisture, dry backs, and root zone temperature.
  • Essential data for crop steering techniques.
  • Support for day and night photoperiods.
  • An Android version and an iOS version of the app. PLUS, an upcoming desktop version.
  • Robust build quality.
  • Offline data logging for crop registration.
  • Multiple connectivity options, including long-range Wi-Fi.
  • Long-lasting battery life with USB power option.
  • Customisable alerts and trend analysis.
  • Dark theme app interface.
  • A sleek, user-friendly app.

The Grow Sensor is the ultimate choice for growers seeking top-tier tools for their cultivation space. 

A note on usability: We’ve paid particular attention to how the Grow Sensor app works and how it looks. We’ve spent a lot of time looking at and comparing light meter apps and PPFD meter apps from the makers of other high quality light meters and grow light meters.

Apps differ wildly, and one thing is for sure: accurate measurement is only part of the equation! A handheld meter that provides light measurement data in a way that’s hard to digest or act on is not handy,

The Grow App outshines other apps owing to its usability benefits. It does a good job delivering all the features of a light meter app in addition to those above whilst minimising the app’s complexity.

The graphs page of the Grows ensor app.

Live graph data and custom alerts

One of the most powerful features of The Grow Sensor is its ability to present PPF readings in live graph form through the accompanying app. 

This visual representation of data is intuitive and incredibly informative. You can track light exposure over time and make precise adjustments to your lighting. 

Whether you're dialling in the intensity for different growth stages or ensuring consistency across your grow space, the live graph data puts a wealth of information at your fingertips.

But we didn't stop at live data tracking. The sensor also allows you to set custom alerts based on your defined PPF thresholds. 

This means you can establish optimal light levels for your plants and receive immediate notifications if those levels are exceeded or not met, allowing for quick corrections. 

This level of monitoring ensures that your plants are always growing under ideal conditions, significantly reducing the risk of light stress or inefficiency.

With live graph data and custom alerts, the Grow Sensor keeps you informed and actively involved in your plants' well-being. It’s an indispensable tool for any serious grower.

An image of a LED grow light under a cannabis plant.

Optimising grow light usage with our PPFD meter

Using our PPFD meter effectively can revolutionise how you manage light in your grow space. 

The sensor is designed for versatility. You can either hang it directly under your grow lights using our specially designed hanging system or mount it on a tripod. 

This flexibility ensures that you can position the sensor at canopy level. Right where your plants interact with the light sources for the most accurate readings.

As your plants grow taller, adjusting the height of your light sources is crucial to maintaining the ideal PPFD levels, and our ambient light sensor makes this task effortless. 

By setting up alerts and limits in advance, you're notified the moment your plants receive too much or too little light. So you can adjust the height or brightness of your lights, fast.

This continuous monitoring means you're always providing the perfect amount of light, mimicking natural conditions as closely as possible, which is key to healthy plant development.

Moreover, the ability to track and adjust your lighting in response to real-time PPFD readings ensures that your plants are not just surviving but thriving. 

With our ambient light sensor guiding your lighting strategy, you can achieve unprecedented control over your grow environment, leading to healthier plants and better yields.

Get early access to the Grow Sensor

Leverage historical data for precision growing

One of the standout features of our Grow Sensor PPFD meter is its ability to store and display historical PPF data in the Grow App. 

This isn't just about looking back but learning and improving. Having access to your grow history allows you to analyse past growing cycles. You can identify what worked well and what could be improved. 

This kind of insight is invaluable for refining your growing strategies and ensuring consistent success.

Historical data plays a crucial role in crop registration, providing a detailed record of your growing conditions over time. This feature empowers you to replicate successful grows with precision. 

Reviewing past data allows you to set the same light conditions that led to your best yields. Turning successful grows into a repeatable formula.

The ability to view and analyse historical PPF data transforms the Grow Sensor PPFD meter from a monitoring tool into a powerful instrument for strategic planning. 

You can react to current conditions and proactively shape future grows based on proven results. Ensuring that every cycle is an opportunity for optimisation.

Affordability and value

In a market where precision often comes with a high price tag, the Grow Sensor stands out for its affordability. Without compromising on quality or functionality. 

Priced at around £500, it offers a suite of features that go well beyond what typical PPFD grow light meters provide. 

From continuous live PPF readings, historical data analysis, custom alerts, and a spectral radiometer. The Grow Sensor sensor delivers comprehensive plant care insights usually reserved for higher-priced devices.

The value of our sensor becomes even more apparent when you consider the cost-effectiveness of its multifunctional capabilities. 

Instead of investing in multiple devices to monitor different aspects of your grow room's environment, the Grow sensor consolidates these functions into one user-friendly device.

This saves you money and simplifies your grow room setup, making it easier to manage and optimise.

When you choose the Grow Sensor, you're not just getting a tool for measuring light. You're investing in a complete grow room monitoring solution that enhances your ability to care for your plants efficiently and effectively. 

It's an investment that pays off in healthier plants, higher yields, and ultimately, greater satisfaction in your growing ventures.


When you grow indoors, having the right tools can make all the difference in achieving lush, healthy plants and bountiful harvests. 

Our PPFD light meter, integrated into the innovative Grow Sensor, is one such tool that stands to revolutionise your approach to plant care. 

With its top-mounted PPF meter for unparalleled accuracy, continuous live PPF readings, the convenience of battery power and a spectral radiometer, it offers a level of insight and control that goes beyond standard PPFD light meters.

The ability to monitor your grow room in real time, set custom alerts, and review historical data means that you're not just reacting to your plants' needs but anticipating them. 

This proactive approach to plant care ensures that your plants get precisely the right amount of light they need to thrive at every stage of their growth.

Moreover, the affordability of our sensor makes it accessible to a wide range of growers. We created the Grow Sensor for home and professional growers alike.

It's a small price to pay for the peace of mind and insight it offers, ensuring that your grow room operates at peak efficiency.

With the Grow Sensor, you can optimise your grow environment and indoor gardening journey like never before, ensuring that your plants thrive.

Happy growing!


How do you test PPFD?

To test PPFD, you use a PPFD light meter, placing it at plant canopy level where the plants receive light.

What is the PPFD for plants?

PPFD for plants refers to the amount of light in a specific spectrum that reaches a plant's surface and can be used for photosynthesis. It's measured in micromoles per square meter per second (µmol/m²/s). 

Different plants have different PPFD needs for optimal growth, depending on their growth stage and type of plant.

What instrument is used to measure PPFD?

A PPFD meter, also known as a quantum meter or a photosynthetically active radiation (PAR) meter, is used to measure PPFD. It measures the light that plants can use for photosynthesis in units of micromoles per square meter per second (µmol/m²/s).

What is the difference between PAR meter and PPFD meter?

PAR meters measure Photosynthetically Active Radiation (PAR) ranges of light that plants can use for photosynthesis. 

PPFD meters, on the other hand, measure the density of this light, specifically how much of that PAR light actually reaches the plant's surface per second. 

So, while PAR meters give you the total light available, PPFD meters tell you how much of that light is actually usable by the plants at a specific location.

Does PPFD change with distance?

Yes, PPFD changes with distance. As you move the PPFD meter away from the light source, the PPFD value decreases because light spreads out and becomes less intense. 

This means plants get less usable light for photosynthesis at greater distances from the light source.

Share this post
Lucy Starley
February 19, 2024
10 min read

Get your free VPD & environment calculator

Perfect your environment.
Stay in the VPD sweet spot.
Ideal temperature ranges for day & night.
Prevent mould.
Induce colour.
Grow the best plants.
We care about your data in our privacy policy.
Your download will land in your inbox shortly.
Oops! Something went wrong while submitting the form.
Screenshot of our FREE VPD chart and environmental calender
Monitor your grow rooms with the Grow Sensor. Access grow room data anywhere, anytime.
We care about your data in our privacy policy.
😉 You have been added to the waiting list.
Oops! Something went wrong while submitting the form.
The Grow Sensor hanging in front of an iPhone displaying an overview of all grows within the Grow AppArrow
Get your FREE impartial list of the best grow room sensors now. Buy the right sensor for your grow room environment.
Sort by price.
Compare features like CO2 & VPD.
Includes affordable & premium sensors.
Check availability in your location.
Make an informed decision.
We care about your data in our privacy policy.
😉 It's on the way to your inbox.
Oops! Something went wrong while submitting the form.
The grow sensor hanging from its cable.
Grow the best plants with your FREE CO2 calculator.
We care about your data in our privacy policy.
😉 It's on the way to your inbox.
Oops! Something went wrong while submitting the form.
The grow room CO2 calculator.
Our blog

Latest blog posts

Get the latest grow news, tips and tricks here.
Learn more about LST and Cannabis by joining our news letter.
Grow The Best

Measuring leaf surface temperature with the grow sensor

Measure your LST! It's crucial for optimising your grow room and improving cannabis quality.
User avatar
Drew Cano
11 Jan 2022
5 min read
Cannabis autoflower vs feminized seeds on a black table top.

Autoflower vs feminised: Pros and cons explained

Discover the pros and cons of autoflower vs feminised cannabis seeds.
User avatar
Drew Cano
11 Jan 2022
5 min read
A scrog net placed over a flowering cannabis plant.

Scrog nets: Worth it or a waste of time?

Learn the benefits and drawbacks of using ScrOG nets and how they can enhance your growing setup.
User avatar
Drew Cano
11 Jan 2022
5 min read
A cannabis grower who is lollipopping there plants.

Boost your cannabis yield with lollipopping techniques

Master lollipopping to improve light penetration and airflow, resulting in top-quality cannabis.
User avatar
Drew Cano
11 Jan 2022
5 min read
Amber trichomes on a cannabis flower.

Amber trichomes: Key to perfect harvest timing

Discover the key to a successful cannabis harvest by understanding amber trichomes.
User avatar
Drew Cano
11 Jan 2022
5 min read
Grow the best - how the grow sensor handles vpd
Grow The Best

The Grow Sensor and VPD

Mastering VPD is essential for optimal plant growth. Learn how to manage it effectively now.
User avatar
Drew Cano
11 Jan 2022
5 min read
Learn your cannabis grow acronyms
Grow The Best

Learn your cannabis grow acronyms

Indoor growing has many acronyms. Learn key terms for better plant growth.
User avatar
Drew Cano
11 Jan 2022
5 min read
A grower holding some of the best soil for cannabis.

Best soil for cannabis: What every grower should know

Find out the benefits of using the best soil for cannabis and how to create your own perfect soil
User avatar
Drew Cano
11 Jan 2022
5 min read