5 Best Greenhouse Thermometers of 2024

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The Best Greenhouse Thermometers

The Best Greenhouse Thermometers
  1. ThermoPro TP55 Temperature and Humidity Monitor

  2. Brannan Digital Max Min Greenhouse Thermometer

  3. ThermoPro TP50 Digital Indoor Room Thermometer Hygrometer

  4. Thermometer World Digital Max Min Greenhouse Thermometer

  5. Outback Blue Digital Min Max Thermometer

Greenhouse Thermometer Reviews

Editors Choice
  • Temperature and humidity readings are displayed in large numbers that are clear to read
  • Data on screen is clearly laid out and easy to interpret, including arrows to indicate if temp/humidity is rising or falling
  • Low battery indicator lets you know when the batteries need replacing
  • Can be hung up or placed on a flat surface using the built-in stand
  • Displays data for the past 24-hour period

  • No clock function so 24-hour data reading is based on when the batteries were first inserted, as opposed to a standard day
  • Can be tricky to locate the backlight button on the touch screen in the dark

If you want an easy way to check on the temperature and humidity, day or night, this ThermoPro TP55 Temperature and Humidity Monitor has a clear screen and useful backlight.

When the ‘lightbulb’ button is pressed, using the touchscreen display, the LCD screen will illuminate for approximately 15 seconds. This gives reasonable time to take a reading, without wasting too much battery. It’s therefore useful for checking temperature and humidity data at night.

The numbers for both the temperature and humidity are sufficiently large and easy to read, and the screen clearly displays other information as well. At a glance, directionally arrows indicate whether the temperature/humidity is dropping or rising, and the unit automatically interprets whether the humidity percentage is considered within ‘dry’, ‘comfortable’ or ‘wet’ levels.

It’s also possible to view the maximum and minimum figures for ‘all time’ or in the last ’24 hrs’. However, it is worth mentioning that there is no programmable clock inside this monitor; therefore, the 24-hour counter begins when you put the batteries in, not at the start of the day. This could be inconvenient if you’re trying to keep an eye over the data over a standard day period.

There are options to either hang the monitor, or prop it up on its own stand. Therefore, you can easily move it around and keep it on any surface, including shelves in the greenhouse.

In terms of accuracy, it seems to generally perform well as both a temperature and humidity gauge for non-professional use. It measures temperature in increments of one decimal place and the manufacturers state that it is accurate to ±1°C.

The display is larger than many similar thermometers, and the dimensions of the whole unit are approximately 8 x 11 cm. Taking this size into account, as well as the clear screen and functional backlight, this is one of the best greenhouse thermometers if you want something easy to read in all conditions.

There is only one minor issue with the backlight, which is worth mentioning – it needs to be turned on via a small button on the touchscreen. And naturally, in the dark this is difficult to see. Therefore, it can take a while to press the correct button to illuminate the display.

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Runner Up
  • Easy to set up in just a couple of minutes
  • Display is very clear and easy to read
  • Can display data in either Celsius or Fahrenheit so it's suitable for all family members
  • IP65 rating means capable of withstanding humid greenhouses
  • Battery included and therefore ready to use straight away

  • Accurate at low temperatures but some customers have found the temperature accuracy decreases as the weather gets warmer
  • Resetting the max/min temperatures is not automatic and needs to be done manually each day
  • Min/max button on the side is small and may be difficult to press with gloves on

Sometimes, all you need is a basic, water-resistant thermometer like this Brannan Digital Max Min Greenhouse Thermometer. It doesn’t overcomplicate things, simply displaying the current temperature, as well as the maximum and minimum.

It’s robust in its simplicity, and its green ABS plastic case has a water and dust resistance rating of IP65 – this makes it suitable for use outside in the greenhouse as well as indoors. IP65 is considered both dust tight and protected from ‘low pressure jets’; as result, it should stand up against humidity, rain and even the odd accidental splash from the hose.

Unlike some of the units featured on this list, this Brannan thermometer doesn’t measure humidity, but it does still display the maximum and minimum temperatures. These are easy to read, displayed in numbers that are the same size as those displaying the current temperature. Resetting the max and min temperatures needs to be done manually, using a small button on the side of the unit.

This button can be a little small to press, especially with gloves on.

However, continuing with the theme of ‘simplicity’, there are only two buttons in total; the other allows you to alternate between Fahrenheit and Celsius depending on your preference. It will measure within the ranges of -10 to +50° in either unit.

It requires 1 x AA battery to run, which comes included, and can be set up in a matter of minutes. All things considered; this is one of the best greenhouse thermometers if you want something easy to use. Its design is simple and uncomplicated, with the added benefit of being waterproof.

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Also Good
  • Easy to reset the minimum and maximum values
  • Instructions are clear and easy to understand
  • Neat portable construction that fits in the palm of your hand
  • Very accurate and it’s easy to switch between Centigrade and Fahrenheit

  • No backlight so you’ll need a torch to read the display in the dark
  • Needs to be reset manually by taking the battery out as there’s no on/off switch
  • Although there is a magnet on the back, there is no screw slot for fixing to non-metal surfaces
  • Takes around 20 minutes to adjust when moved to a different room or subjected to a big change in temperature

Greenhouses aren’t renowned for having loads of free space, which is why it helps that the ThermoPro TP50 Temperature and Humidity Monitor is a particularly compact device – measuring just 7.8 x 6.6 cm. It fits roughly into the palm of your hand.

It can be positioned wherever there’s sufficient space, with a hanging option as well as a built-in stand and magnetic back. If you’re really low on room, you could even attach it to a metal watering can.

Even though the unit is compact, it still clearly displays humidity and temperature readings. On top of showing the current data, it also shows ‘low’ and ‘high’ readings from the last 24 hours, and indicates whether the humidity is considered ‘dry’, ‘comfortable’ or ‘wet’.

Compared to the small Brannan Greenhouse Thermometer, the ThermoPro TP50 is capable of measuring a much larger range of temperatures, from -50°C to 70°C, and it can display its readings in either Celsius of Fahrenheit.

According to the manufacturers, it’s accurate to ±1°C, and reports from customers seem to support this claim. Whilst not precise enough for professional use, it should give a good overall impression of the temperature and humidity inside the greenhouse.

Unlike its larger sibling, the TP55 (also featured on this page), this TP50 doesn’t have a backlight so it’s not particularly easy to read in the dark. Nevertheless, with the use of a torch it should still be easy enough to interpret main data; despite this unit’s small size, the numbers are still quite large.

It’s one of the best greenhouse thermometers if you need something small and compact. Plus, it has the added bonus of people able to affix to many different surfaces, depending on where will save the most space.

It requires 1 x AA battery, which comes included.

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  • Buttons on front are easy to press to change between Celsius/Fahrenheit and reset values
  • Display is clear and easy to read
  • Small and lightweight so is appropriate to hang in various areas of greenhouse
  • Comes with 1 x AAA battery included

  • No official waterproof rating so should not be exposed to excessive moisture like rain
  • Doesn’t give an accurate reading if left in direct sunlight
  • Can overheat if left in direct sunlight in greenhouse

One of the best greenhouse thermometers if you’re after value for money, this Thermometer World Max Min Thermometer has a simple, clear screen that displays three sets of data.

In the middle, the largest numbers show the current temperature. Then, above and below, the maximum and minimum temperatures are displayed as well. These can be measured over any period of time, as they are reset manually.

It’s a useful tool to have hanging in the greenhouse, and the manufacturers claim that it is accurate to ±1°C. This makes it suitable for working on a variety of tasks, such as keeping an eye on max/min temperatures during seed germination.

The plastic casing is relatively robust, and has a hole cut out in the top that makes the thermometer easy to hang. However, unlike some of the other thermometers featured here, it doesn’t have an official waterproofing rating – rain can get inside if it’s left outdoors in the garden. Nevertheless, it seems to work well in greenhouses without being negatively effected by humidity.

Whilst the design has a built-in ‘roof’, this doesn’t do much in regards to protecting the thermometer from either rain or sun, and it’s best to keep it out of direct sunlight as well to avoid overheating.

This thermometer is straight forward to use and comes with 1 x AAA battery included which is all that’s required to start it running. It’s sufficiently accurate if you want a small, easy-read thermometer that offers good value.

It can also be changed between Celsius and Fahrenheit depending on your preference.

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  • Responds quickly to temperature changes
  • Display clear and easy to read and interpret
  • Powered by 1 x AAA battery that comes included
  • Very easy to switch between Centigrade and Fahrenheit
  • Readings appear to be accurate and the values are easy to reset

  • No humidity reading so you may wish to purchase a humidity monitor separately
  • Although designed for indoor and outdoor use, it’s not fully waterproof so should be installed in a sheltered spot

Budget thermometers can be wildly inaccurate, but this Outback Blue Digital Min Max Thermometer gives a useful reading whilst being clear, easy to use, and yes – inexpensive.

In appearance, its design is similar to the Thermometer World device also featured on this page, with an almost identical shape and layout. This Outback Blue Thermometer measures 15 x 7.5 cm and displays the current temperatures, as well and the maximum and minimum temperatures.

There are also two buttons on the front that are easy to use and see; one button is for alternating between Celsius and Fahrenheit, and the other for resetting the max/min temperature.

It has a white plastic casing, described as ‘water resistant’. Most customers seem to have found this description accurate, and that the thermometer is not easily affected by small amounts of moisture, be that light rain, or humidity inside the greenhouse.

In terms of accuracy, it generally seems to be correct to ±1°C, so whilst not a professional device, it’s useful for general gardening. The total temperature range available is -50°C to + 70°C, although it can get a little less accurate during very hot summer temperatures.

Overall, taking into account this thermometer’s accuracy, ease of use, and cost, it’s one of the best greenhouse thermometers to buy on a budget. Whilst it might not be as precise as more expensive thermometers, it offers good quality and for the price and will provide useful readings.

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Clive's Smart Buying Tips

  1. For taking basic temperature readings, look for a wireless digital thermometer that shows min/max temperature data as well as the current temperature. Thermometers that show maximum and minimum temperature over a certain period are really useful, as these allow you to see how much temperature variation your plants are experiencing. You can then plan ahead to keep your greenhouse’s temperature more consistent.
  2. I recommend a digital thermometer over a traditional analogue model. The displays are clearer and easier to read and interpret. You may wish to look for a thermometer that doubles up as a hygrometer (measuring humidity as well as temperature). These give a broader overview of growing conditions.
  3. Another useful feature to look out for is a backlit display. These come into their own when reading the thermometer data in low-lighting conditions, so they are ideal if you like to check the greenhouse temperature in the evening and early morning.
  4. A weatherproof ‘IP’ rating can also be helpful to look out for. Given that greenhouse thermometers will be used in damp conditions, an IP rating of IPX5 can ensure there’s no water ingress. Without an IP rating it’s hard to know exactly how watertight something is. 

Overall, I’ve chosen the ThermoPro TP55 Temperature and Humidity Monitor as my top recommendation. This digital thermometer measures temperature and humidity, and displays min/max temperatures from a 24-hour period. It has a clear, backlit display and large easy-read screen. However, bear in mind that it doesn’t have an IP rating.

How to Choose the Best Greenhouse Thermometer

Keeping a close eye on the temperature inside your greenhouse is vital for the health of the plants. Certain plants require different temperatures to flourish, and if the greenhouse is too hot or too cold, they will struggle to carry out necessary processes like photosynthesis.

Greenhouse thermometers are a great way to monitor the temperature without a lot of effort. Here you will find some useful information to help you choose the best greenhouse thermometer.

READ NEXT: The Best Polycarbonate Greenhouses

LCD Digital Displays

Digital displays are the easiest way to quickly read the temperature of a thermometer at a glance. Other types of thermometer are available, such as spirit thermometers. These work in the same way as old, traditional mercury thermometers (which are no longer manufactured) and feature a glass tube with liquid inside it. Whilst spirit thermometers tend to be reliable, it takes longer to interpret the data and human error can impact the reading.

Digital displays are easy to immediately interpret, and they are clear and easy to read. Thanks to the nature of the digital instrument, it’s easy to buy a digital thermometer that displays a variety of data, not just the current temperature. There are digital greenhouse thermometers that will display the maximum and minimum temperatures over a period of time, as well as the humidity.

Additionally, some digital thermometers have a backlit display which makes the thermometer easy to read in low light – this can be particularly useful when checking on temperatures in the evening and early morning.

READ NEXT: The Best Pop Up Greenhouses

Maximum/Minimum Readings

As mentioned, a lot of digital thermometers will provide max/min temperature readings as well as the current temperature. But why is this useful?

Temperatures in greenhouses can fluctuate dramatically, especially between day and night. This may not be ideal for the health of plants, but it’s difficult to check up on with a standard thermometer.

If a thermometer can show the maximum and minimum temperature over a certain period (for example, 24 hours), you’ll be able to check if the temperature is getting too low or high. This information can allow you to make decisions, such as installing greenhouse heaters, in order to maintain more consistent temperatures.

Some max/min thermometers will automatically reset after 24 hours, whilst others will need to be manually reset when required.

In addition to max/min temperature readings, there are also more advanced digital thermometers that will also display the maximum and minimum humidity readings over a certain time period. Again, this can be useful to keep an eye on for certain types of plant.

Different Levels of Weatherproofing

Some thermometers don’t mention any form of weatherproofing, in which case you should presume that they haven’t got any. For a greenhouse thermometer to be long lasting and effective, it should ideally at least describe itself as ‘water resistant’.

Digital thermometers will be more likely to succumb to weather-related problems compared to spirit thermometers, purely due to their electronic nature. Therefore, it’s important to make sure they have some water resistance.

The best thing to look out for is an ‘IP’ rating, as this means that the thermometer has been properly tested against dust and/or water ingress. The second number refers to how protected the product is against water. Ratings of IP65 and over should are generally considered ‘waterproof’ and should stand up to most every-day conditions. They may not survive being submerged in water, but should withstand the damp and humid conditions of a greenhouse.

READ NEXT: Ways to Heat a Greenhouse in Winter Without Electricity

Greenhouse Thermometer FAQs

You should avoid placing your thermometer in direct sun. This will give readings that do not reflect the overall temperature. You can shade the top of the thermometer with foil to help prevent this. In general, it’s best to place the thermometer about mid-height and away from doors, windows and heat sources. Remember that the temperature will be a little higher above the thermometer and a little lower below it.

Of course, if you have specific plants you want to protect, then place the thermometer near these to check the temperature in that specific area.

Digital thermometers are generally easier and quicker to read. The temperature is displayed numerically, instead of needing to be interpreted (as is the case with a spirit thermometer). They also remove the element of human error, which may come into play when reading a spirit thermometer. The biggest downfall of digital greenhouse thermometers is that they are not always sufficiently waterproof. This can mean that water and humidity gets in, which isn’t a problem with glass spirit thermometers. However, this problem can be avoided by buying a digital greenhouse thermometer with a sufficiently high waterproof rating.

Firstly, a digital thermometer with a backlit screen will make it physically easier to read the temperature. Not all digital thermometers have a backlit screen, but if they do, there will generally be a button to turn it on. The screen will illuminate for a few seconds before turning off again to save battery. You can also keep an eye on the maximum/minimum temperatures overnight by buying a max/min thermometer. You can reset it as night falls, and check the readings in the morning to get an idea of the night time temperatures.

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