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.
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.
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.
Greenhouse Thermometer FAQs
Where is the best place to position a greenhouse thermometer?
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.
Should I buy a digital greenhouse thermometer or a spirit thermometer?
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.
Is there a way to make it easier to take temperature readings at night time?
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.