Plant Sensors 101
Everyday we get a lot of the same questions and misconceptions about plant sensors and plant science. Maybe you’ve bought plant sensors before and they don’t work, or you’ve yet to meet a plant sensor that works better than your green thumb.
Maybe you’re overwhelmed by all the options and don’t even know where to start.
What’s clear is that choosing a sensor isn’t as easy as picking one that says it will keep your plant healthy–there’s a lot of bad science out there, so how do you navigate it?
We got our start in academia and biotech, so we believe the science of plants demands precision. Our goal is to help you understand the science, so you can navigate the complex world of plant sensors.
We’ll clarify the FAQ, debunk some common misconceptions, get into how plant sensors work, why they are so cool and important for plant health, and why you might want to add them to your plant care routine.
What are plant sensors?
At its most basic, a plant sensor needs to measure plant health. Not all plant sensors measure plant health equally, their efficacy varies based on the types of technology used.
What does a plant sensor measure?
Some plant sensors only measure one variable (i.e. light or temperature), while others can measure multiple at once. You’ll want to look for a plant sensor that can at least measure temperature, light, moisture, and humidity, as those are the most important variables for determining overall plant health.
Standard vs Specialty Plant Sensors
There are two types of sensors: standard and specialty. While standard sensors tend to be cheaper, they’re not as accurate or precise. A specialty sensor like leaflet utilizes tech similar to Precision Agriculture technology to give the most precise and accurate health measurements.
Proven Precision Accuracy
Look for sensors with proven precision accuracy. Performance claims have become a marketing tool recently, so be wary of the sensors that claim they’re accurate with no evidence.
Precision accuracy was a term that used to be exclusive to Agriculture, it’s how performance of plant sensors is determined. Precision refers to the degree of consistency of a sensor's measurements, and accuracy refers to the degree of correctness of a measurement. It’s generally indicated in percentage. The lower the number, the more accurate it is.
For example, a precision accurate plant sensor is able to measure the true moisture content of the soil consistently over time.
Standard sensors are within ±15-20% accuracy, which means the measurements they provide are unreliable, and will vary by day and placement. Specialty plant sensors like leaflet have proven precision accuracy, which means their measurements are AgTech grade and consistent.
Until Leaflet, high performance was exclusive to AgTech, because the necessary instruments were thousands of dollars. We combined $3000 worth of AgTech sensors into one device, and lowered the cost to make it affordable. So unlike standard sensors, Leaflet is the science of AgTech, designed for your home.
Some of you may be used to buying sensors as separate devices. You’re used to breaking out a moisture meter, a digital thermometer, etc. The idea of having one sensor do it all and keeping it one plant at all times probably seems odd–or even pointless.
So what is the benefit of one device for one plant? Well when you measure humidity, temperature, light, and moisture separately, you miss out on the biggest benefit of plant sensors: proactive care.
Like taking a picture of the moon on one night only shows you a partial view of its cycle, using a sensor at just one moment in time only gives you a snapshot of the problem. That’s why we designed leaflet to give you the entire picture.
The biggest difference between speciality and standard sensors is data. Standard sensors are used as a diagnostic tool, only when something looks wrong–they are reactive. Moisture, temperature, light, and humidity are treated as separate entities, not a whole.
A specialty sensor like leaflet uses data over time to create a holistic view of your plant health. Plant health is updated in real-time, allowing you to stop problems before they start–they are proactive.
How do plant sensors work?
A specialty plant sensor can measure light, moisture, temperature, and humidity at once, It has proven precision accuracy. It’s proactive, not reactive. But what is the difference between standard and specialty plant sensor technology, and how does it work? What other important technology is necessary to make plant sensors work?
When we first started Krado, we learned standard sensors were measuring light in binary–is there light, yes or no?–which is not very informative for plants. Many plant care apps or sensors can tell you a plant needs “low light” but can’t specify what kind of light the plant needs.
Plants absorb light on the entire spectrum, so we knew if we wanted to accurately tell you what kind of light your plants needed, we needed a better way to measure it.
That’s why we don’t just measure quality and quantity of light, we measure the entire spectrum, and we’ve quantified light down to the photon.
Leaflet has both an AgTech grade PAR Meter and Spectrometer. Leaflet can distinguish both indirect and direct light, intensity and quality, as well as the visible and infrared spectrum. Leaflet is also calibrated to measure the number of photons, improving data accuracy.
The most common type of temperature sensor used in standard sensors is a digital thermometer, and they have an accuracy of around ±1°. We designed leaflet’s temperature sensor to be within 0.4° accuracy.
The most common type of technology used in standard moisture sensors is electrical conductivity (EC). We’ve found the accuracy of standard sensors to be unreliable (an accuracy of about ~15%). This unreliability stems from a number of problems:
- Soil salinity: EC-based moisture sensors can be affected by the salt in the soil, which can interfere with the accuracy of the readings.
- Soil compaction: If the soil around the sensor becomes compacted, it can affect the ability of the sensor to accurately measure moisture levels.
- Sensor drift: Over time, EC-based moisture sensors can experience drift, which means that the readings become less accurate over time.
- Sensor placement: The accuracy of EC-based moisture sensors can be affected by the placement of the sensor in the soil.
This is why Leaflet uses an AgTech grade capacitance soil moisture sensor. Our proprietary technology delivers the high performance of AgTech soil moisture sensors at a fraction of the cost. The accuracy of our soil moisture sensor is 2%. For more in-depth information, check out our experiment.
There are a few different technologies used in standard humidity sensors, most use resistive or capacitive technology. Leaflet’s humidity sensor is within ±2% accuracy.
The accuracy of humidity sensors can be affected by factors such as temperature, light, soil moisture–which is why it’s so important to take all variables into consideration.
As we discussed earlier, most sensors are used as diagnostic tools, which means they’re missing out on the biggest benefit–proactive care. The difference between proactive and reactive care is plant data.
Leaflet is constantly learning and optimizing. The more people we have on our platform, the more intelligent your leaflet gets, and the more personalized your care becomes. This allows us to do neat stuff like:
• Adjust settings to your microclimate
• Suggest the right plants for your home and microclimate
• Alert you when your plant needs a new pot
• Optimize settings for plants that don't even have sensors
• Send you plant products based on sensor insights
• & more!
We share the data unlocked by our sensors in your app to help you grow more easily. We also use the data to send you the plant products your plants need.
Check out our case study and see how we used plant data to stop root rot before it happened! Or learn more about our goal is to build the first ever plant database and share it with the world. Every time you use leaflet, you contribute to that goal and help further botanical research. Curious how plant data can be used to change plant care? Keep reading!
Using Data to Create a Holistic View of Plant Stress
VPD, or Vapor Pressure Deficit, is the current industry standard used to determine “plant stress.” VPD is a measure of the difference between the amount of moisture in the air and the maximum amount of moisture that the air can hold at a particular temperature. TLDR: VPD uses two variables, temperature and humidity.
However, what we're learning through all this awesome new plant data at Krado is that even VPD is too simple, as it only takes two variables (humidity and temperature) into account. So at Krado we use all plant health variables (humidity, temperature, light, and moisture) to calculate plant stress. As we add more features to our sensor, those will be included into our calculations as well.
In this way, we create a truly holistic view of your plant health in a way that has never been done before.
What are plant sensors good for?
So you’ve found the right plant sensor. It’s proactive and gives you a holistic view of your plant health–now what? What are they good for?
Proactive Plant Care
A good plant sensor will stop problems before they start.
Ever searched online for plant advice? You enter “yellow leaves” and get a plethora of conflicting advice–too much water, no too little, wait it needs to be repotted, no leave it alone. With a sensor, you get advice directly from your plant.
Optimize your plant care routine
Plant sensors will help optimize watering schedules, detect pest and disease issues, and promote overall plant health. This means you:
• Save Time
Did you know the average house plant owner spends 17 to 26 hours per year watering plants alone? Using leaflet, you only water your plants when they need it.1
• Save Money
Did you know the average person wastes $500 on dead plants yearly?2 Plants can live for decades when cared for properly–they can become family heirlooms!
• Reduce Waste
The average person uses 104-260 gallons of water per year to water plants.3
• Save Water
Maybe it feels like throwing away a dead plant is no big deal–it’s a plant, Michael, how much waste can it produce? Did you know 95-98% of plastic pots end up in landfills?4
Improved Plant Health & Look
A specialty sensor will keep your plants looking healthier, more radiant, and they’ll bloom longer–sometimes plants you didn’t know could bloom!
Keep plants alive longer
• Problem Plants
Maybe you think you suck at succulents, but with a sensor there’s no such thing as a problem plant.
• Invest in expensive or rare plants
Sensors are perfect for expensive and rare plants–the investments you want to protect.
With a sensor that monitors your plants health in real-time, you can keep track of your plants on vacation, traveling, hiking–wherever!
Choosing your plant sensor
Hopefully by now you have a good idea of which sensor is right for you. You probably know if you want a standard or speciality sensor, understand and can spot the bad science. So here we’ll go over a few common misconceptions, and a few other things to consider when choosing your plant sensor
Sensors with Data & AI
The most important thing to look for in a plant sensor is data, because plant data gives a holistic view of your plant health. Data and AI have become a marketing tool, so here’s how to spot the real from the fake:
Sensors Used with Bluetooth vs WiFi vs Cloud
If sensors use bluetooth or WiFi only, then your plant data isn’t being used to create a holistic view of plant health. Leaflet’s data is uploaded to our cloud, so not only do your plants learn from each other, but they learn from all plants in our system.
Sensors as a Diagnostic Tool
Sensors marketed as diagnostic tools misunderstand how plant science works. Especially pay attention to plant sensors that claim to be both “proactive” but can be used as a “diagnostic tool” as this is a fundamental misunderstanding of plant science.
Sensors Paired with Multiple Plants
Look out for sensors that claim they can be paired and unpaired with multiple plants. This is a new marketing tactic, and not how plant science works.
Some sensors have a user friendly app that will translate sensor readings into easy to understand advice. Considerations with this are:
Do you have to pay for the sensor and the app? Or is the cost bundled? Are there hidden costs inside the app? For plant owners, prices can quickly skyrocket when factoring in the amount of plants they own. This is why we chose to bundle our app, sensors, and personalized product delivery into one yearly cost.
The Type of Advice
Leaflet only sends data-backed advice via sensor insights. While it might seem personalized, without sensor insights, app advice will be generalized (similar to searching “yellow leaves” and receiving a lot of conflicting advice).
How important is battery life to you? Leaflet’s battery life is 3-4 months and is easily recharged with a USB-C cable.
Look & Design
Your plants look beautiful, so your sensor should look beautiful too. It’s up to you to determine what kind of style you like. We really didn’t like current sensor designs, so we set out to design Leaflet with a few goals:
• No exposed charging ports
Leaflet has won Bronze Spark Award & is an IDSA Featured Finalist. We’re also the first to use 3D-Additive Manufacturing with Biodegradable Plastic. Old manufacturing with silicone and plastic isn’t just bad for the environment, it’s wasteful.
Sensor Q & A
What is DLI?
DLI or “Daily Light Integral” is a measure of the total amount of light that a plant receives over a 24-hour period, usually expressed in units of mol/m²/day. Read more in our article Demystifying Daily Light Integral
What is VPD?
VPD, or Vapor Pressure Deficit, is a measure of the difference between the amount of moisture in the air and the maximum amount of moisture that the air can hold at a particular temperature. TLDR: VPD uses two variables, temperature and humidity.
What is plant stress and how is it measured?
VPD, or Vapor Pressure Deficit, is the current industry standard used to determine “plant stress.”
Is a plant sensor a moisture meter?
A moisture meter is a type of standard plant sensor.
Are cheap moisture meters accurate?
We’ve found the accuracy of standard sensors (of which moisture meters are included) to be unreliable with an accuracy of about ~15%. For a more in depth analysis, check out our experiment.
- Calculated by starting with the assumption that the average owner spends around 20-30 minutes per week watering their plants. We multiply this by 52 weeks in a year, we get an estimate of around 17 to 26 hours per year spent watering plants.
- 2021 National Gardening Survey. Garden Research. (n.d.). Retrieved March 31, 2023, from https://gardenresearch.com/view/national-gardening-survey-2021-edition/
- According to the Environmental Protection Agency (EPA), the average American household uses around 320 gallons of water per day, which includes indoor and outdoor use. Assuming that a plant owner accounts for a small portion of this water usage, we can estimate that they may use around 2-5 gallons of water per week to water their plants, depending on the number and type of plants they have. Multiplying this by 52 weeks in a year, we get an estimated range of 104-260 gallons of water per year used to water plants by a plant owner.
- Environmental cost of plastic plant pots. Environmental Cost of Plastic Plant Pots | American Public Gardens Association. (2021, January 6). Retrieved March 31, 2023, from https://www.publicgardens.org/events/environmental-cost-plastic-plant-pots