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It seems straightforward: give plants enough light and water and watch them grow. Unfortunately, it’s easy to get in your own way, especially when it comes to watering. Maybe you’re the type to give plants too much attention (and water) and end up with root rot and dead house plants. Maybe you’re the opposite – you’re prone to forgetting to water your house plants until it’s too late. That’s where a plant water meter comes in to save you and your houseplants.
A plant moisture meter is a simple gardening tool and a real game-changer. It takes the guesswork out of watering plants, especially finicky plants like succulents and orchids that can rot quickly with too much love.
A good moisture meter for plants doesn’t need to be complicated; in fact, the simpler, the better. The plant moisture meter I use most often is as basic as it gets and helps me keep my delicate succulents and pineapple plants alive. Still, you can get extra features like pH sensors to really step up your gardening game.
Here’s how to choose the best plant moisture meter for your needs and my picks for the best moisture probes.
How to Choose the Best Plant Water Meter
Plant moisture meters may look pretty similar, but they can vary significantly in durability, accuracy, and features. For most gardeners, a basic moisture probe without bells and whistles will suffice, but you should consider where and how you will use the meter and the measurements you’ll need to choose the right meter.
Garden Use or Indoor Plants
Most plant moisture monitors are suitable for potted plants or houseplants. If you plan to use the moisture meter outdoors, you should definitely consider probe length. A smaller probe won’t work in the garden because it won’t reach the roots. You will also want a more durable probe for garden soil which is usually harder than potting soil and may have small rocks.
Digital, Analog, or Color Change
An analog water meter is an affordable, basic option and it works well enough for most gardeners. You will get a moisture reading on a scale of 1 to 10, usually with color coding. A digital moisture meter is a bit more expensive but it will be more accurate and easier to read. The drawback is it will require batteries. The most basic type of technology is a color change plant watering stick which fades or darkens to indicate soil moisture. These water meters work like a wick.
Do you want to track data over time or check soil moisture and other readings remotely? There are very few options for smart plant monitors, but the models available let you connect the moisture meter to a gateway and monitor multiple plants or even track moisture, pH, and nutrient levels through an app. The tradeoff is the addition of technology can make the meters less accurate or more difficult to use.
Think about the measurements that are most important for you to track. A plant water meter is the most basic option and the most accurate measurement. A probe that measures soil pH can also be very accurate and effective for amending soil and tending to sensitive plants.
Light measurements can be helpful for making sure your plants are in a good location, but you are usually better off getting a dedicated light meter.
Soil nutrient meters included with water meters usually only measure nitrogen, phosphorus, and potassium. This feature may be helpful for certain plants like tomatoes to help you detect nutrient deficiencies.
If you will use the probe in a harder soil like clay, make sure you choose a sturdy probe that’s at least ¼” thick. For looser soil and potting soil, most probes will be sufficient.
A basic analog plant moisture meter is good enough for the average gardener and typical plants. If you are caring for special or fussy plants and need greater accuracy, a digital moisture meter is a better option. The ability to calibrate the meter can make it even more accurate because you can adjust for humidity, soil type, or moisture requirements.
Overall Best Plant Moisture Meter
When accuracy and ease-of-use matter, the simpler the design, the better. That’s what makes the XLUX Soil Moisture Meter the overall best moisture meter on the market.
No batteries and no calibration necessary – just insert the probe into the soil for an instant moisture reading. The dial has a 10-point scale with easy-to-read color-coding: blue for wet soil, green for moist soil, and red for dry soil.
Unless you have very fussy plants and need the extreme accuracy of a properly calibrated digital soil moisture probe, this basic XLUX plant hydrometer will serve you well.
Best 3-in-1 Plant Monitor
Most sensors for plants are designed to detect soil moisture only. If you want to make sure your plants are getting enough light and have the right soil pH for optimal growth, the Fivota 3-in-1 plant monitor is your best bet.
This analog meter has sunlight sensors on the top and sides of the display with two probes: one for pH and one for moisture. The large rectangular screen is easy to read and labeled with color-coding.
Use the Fivota soil moisture tester to verify plants have the ideal amount of water, test the amount of sunlight house plants are receiving in the windowsill or in the garden, and test the soil pH so it can be amended if necessary.
There are some things to keep in mind. The sensors are very delicate – don’t drop the plant meter or insert it into very hard or very dry soil. It can’t be used to test artificial light. If you’re using grow lights, you’ll want to use a PAR meter to measure PPFD. This will help you choose the right grow lights and place your plant properly so they aren’t scorched or starved of light.
Best pH & Moisture Probe
The Kensizer tester is the best soil moisture meter for plants with an included soil pH meter. Many moisture and pH meters have a two-probe design that’s more fragile and harder to insert into soil. Those designs usually have a switch for toggle between pH and moisture testing which can break over time. The single-probe design of the Kensizer plant moisture meter is far more durable and easier to use.
You get two probes: one is used to test pH and one tests soil moisture. You’ll need to insert the probe about 2-4” then wait about one minute for a stable reading. The soil pH tester will definitely come in handy if you’re amending soil and need to keep it within a good range or you’re growing plants that like acidic soil like caladium or azaleas.
Best Soil Moisture Meter for Deep Pots
Most moisture sensors for plants have a probe that’s 7” to 9.5”. That’s perfectly suitable for most houseplants and checking soil moisture in a raised garden bed, but it won’t work well for monitoring soil moisture in deep pots. That’s because you want to measure the moisture close to the roots and deeper in the pot to make sure the water is getting where it’s needed – and the roots aren’t drowning while the topsoil dries out!
The XLUX Long Probe water gauge for plants has a 40cm (15.75”) probe. It’s otherwise the same as the regular XLUX meter I love which has a 26cm (10.25”) probe. This should be long enough to check the moisture in even the deepest plant pots.
Best Soil Moisture Meter for Indoor Plants
Most plant monitors are designed to be inserted into the soil as needed to check soil moisture and/or pH. If you leave the metal probes in the soil for too long, they’ll get corroded and stop working.
If you’re looking for a leave in soil moisture meter, you’ll appreciate the Sustee potted plant moisture meter. These simple plant watering indicator sticks are designed to be left in the soil with a color changing sensor that lets you know at a glance when it’s time to water.
You can buy the Sustee Aquameter in three sizes: small, medium, and large. Make sure you get the right size for your pot to get accurate moisture readings.
The Sustee is definitely the best moisture meter for plants that are indoors and finicky when it comes to soil conditions. The company worked with the Toyko University of Agriculture to develop the award-winning design that’s intuitive, simple, and attractive.
There are some drawbacks to the Ippinka Sustee Aquameters. It takes up to 25 minutes for the indicator to change color and give you an accurate soil reading for the large indicator or three minutes for the small stick. They aren’t designed for instant results. Instead, these plant monitors are best used for monitoring indoor plants over time to make sure they’re watered thoroughly and let you know when the soil dries out.
I use the Sustee soil moisture meters for a few of my plants that need moist soil and don’t do well if they dry out. I’ve tried them outdoors in the summer but the humidity combined with 90°+ heat seemed to render them useless. Even when the soil was completely dried out, the sensor was still blue, probably because of the high humidity.
Another drawback is you’ll need to replace the color-changing core every 6 to 9 months. Sustee moisture sensor refill packs are fairly affordable.
Best Digital Soil Moisture Meter
The Ecowitt Soil Moisture Tester is a unique water indicator for plants with an easy-to-read LCD screen combined with a short, flat 3-inch probe, not a long, thin probe that’s more prone to damage.
The LCD screen displays the time and the moisture level in soil as a percentage and with a visual representation. You’ll get an accurate reading within 2-3 minutes and have the ability to manually calibrate the high and low moisture values for even more accuracy.
The Ecowitt Soil Moisture Sensor is waterproof and it can be left in the soil with the LCD display indoors. It transmits wirelessly up to 300 feet. If you add the GW1100 gateway (which also works with other Ecowitt sensors), you can have up to eight channels for additional Ecowitt moisture sensors.
For most people, the Ecowitt plant moisture indicator and LCD screen is enough. It’s accurate and easy to use, but there are a few drawbacks. The probe is very short at just 3” so it’s best for smaller pots or plants with shallow roots. According to Ecowitt, the moisture probe is IP66 waterproof which means it should be protected against “powerful water jets” like sprinklers and rain. It isn’t rated for immersion, and it doesn’t seem durable enough to hold up to outdoor conditions if it’s left outside.
If you’re looking for an accurate soil moisture meter for indoor plants, the Ecowitt is a solid choice. It’s more expensive than the Sustee moisture indicator sticks but far more accurate, displaying soil moisture as a percentage with the ability to calibrate it manually. The LCD screen and wireless transmission makes it easy to monitor plants from a more convenient location.
Best Smart Moisture Meter for Plants
If you’re set on smart technology, the Wanfei plant monitor is the best moisture meter you’ll find. There just aren’t many smart soil moisture monitors on the market. However, try it at your own risk – many people run into serious issues connecting to the sensor and app without a VPN and the mandatory app leaves a lot to be desired.
The Wanfei nutrient, light, and water meter for plants uses Bluetooth connection and the Flower Care app. To test soil, you need to first select a plant type then region. The app is mandatory yet gets very little in the way of updates and it has a limited database of plants. You’re required to select a plant in the app before testing the soil. The Wanfei plant sensor states that you shouldn’t update the Flower Care app to the newest version or you will essentially brick your device – a big red flag. If you’re able to set it up and select “USA” as the region, it may be unable to connect unless you use a VPN server in China.
Another thing worth noting: a product with the exact same design and images has been marketed for years under different names including the “Xiaomi Smart Plant Monitor,” “Northfifteen Connected Home Plant Monitor,” and “Flower Care” or “Grow Care.” The marketing on the listing still refers to it as a “Grow Care unit.”
If you’re able to get around that issue, which isn’t reported by everyone, and you’re fine with a limited database, the Wanfei plant monitor may be worth trying. Just don’t expect much “smart” from the smart sensor.
If you do decide to give the Wanfei smart plant watering sensor, you might also be interested in their smart plant pot designed to monitor soil moisture and nutrients in real time. It might be fun to try but again, don’t expect much.
Moisture Meter FAQs
A moisture sensor for plants is a basic hygrometer that is used to measure moisture in soil. A hygrometer doesn’t actually measure water in the soil: it measures conductance or the electrical current flowing between two probes. A meter with a single probe has an electrode tip and a metal shaft with plastic separating the two. The more water in the soil, the higher the conductive reading.
To use a plant water meter, insert the probe carefully into the soil at least 4 inches or 4/5 of the way in. Do not force the probe into the soil: very hard soil or rocks can damage the sensitive probe. If your hygrometer has two probes, it should be inserted vertically. Wait about 1-3 minutes then check the reading. If your plant needs water, test again a few moments after watering. After using a soil water meter, make sure you wipe the probe clean and store it dry.
A moisture probe is accurate enough for gardeners to give most plants the right amount of water. An affordable analog soil water meter will measure moisture on a scale of 1 to 10. A digital soil moisture meter is far more accurate than an analog model and gives you a measurement as a percentage or a reading to the closest decimal point. Some issues like a high level of salt can give you inaccurate readings. Soil moisture sensor accuracy is a challenge even in the agricultural industry using commercial-grade sensors, but most inexpensive soil moisture meters are accurate enough for the typical gardener.
The average moisture meter for houseplants is not designed to be left in the soil. Meters with sensitive, thin probes will become degraded quickly if you leave them in the soil. Look for a model designed as a leave in soil moisture meter such as the Sustee aquameter or the Ecowitt moisture meter.