Digital greenhouse thermo-hygrometer, with or without probe
This digital thermo-hygrometer displays the air temperature and humidity in a greenhouse, a grow tent or a seedling room. The Medium and Premium versions add a remote probe, which measures at a second location, and run on one AAA battery.
The summary
- The package: the thermo-hygrometer of the chosen version, with its remote probe and an AAA battery in Medium and Premium.
- Greenhouse air: the air temperature and relative humidity, displayed continuously.
- Which version: Basic for a single measuring point, Medium or Premium to monitor a second location as well.
- Accuracy: to within 1 °C and 5% humidity on the Premium version.
- The useful benchmark: keep the greenhouse air below 85% humidity to limit grey mould.
- Above the tank: a reading of the greenhouse air, to be supplemented with a thermometer for the tank water.
Air temperature and humidity for greenhouse, grow tent and seedling room
The Garden HighPro digital thermo-hygrometer shows the air temperature and relative humidity in a greenhouse, a tent or a seedling room. The Basic version measures at a single point, while the Medium and Premium add a remote probe. Above a fish tank, it flags air that is too humid, as the water is monitored separately.
In a greenhouse, temperature and humidity change from hour to hour, and what you feel when opening the door at midday tells you nothing about the night before. This digital thermo-hygrometer continuously displays both values on an LCD screen, to stand on a shelf or fix to the wall, at the height of your plants. The range comes in three versions: the Basic measures where it sits, while the Medium and Premium add a remote probe, connected by a cable, which takes the temperature at a second spot. The Medium and Premium versions run on an AAA battery, supplied.
🔍 What sets each version apart
Basic
The entry-level model shows temperature and humidity at the spot where it is placed, with no cable or probe.
Medium
It adds a remote probe and a 5 x 5 cm LCD screen, in a slim casing 1.7 cm thick.
Premium
Its 6.5 x 7.5 cm screen can be read from a distance, and its probe has a 1.5 m cable.
The Premium version measures temperature from 0 to 50 °C with an accuracy of 1 °C, and relative humidity from 25 to 90% with an accuracy of 5%. It also records the temperatures taken, which lets you know the value reached during the night. Its 12 x 9 cm case can be fixed to the wall or laid flat, and its probe, at the end of its 1.5 m cable, slips into a propagator or under the lid of a seed tray while the display stays readable on the outside.
The remote probe under the seedling lid
With the Premium version, the display stays on the shelf and the probe goes under the dome of a germination tray or into a mini greenhouse placed on a heat mat. You can then read the temperature that actually prevails around the seeds, without lifting the lid and without losing the accumulated humidity. The reading tells you at once whether the mat is heating too much or too little for the species sown.
A device designed for indoor use
The thermo-hygrometer and its probe are designed for indoor use, in a greenhouse or grow room. Place the display away from watering splashes and out of direct sunlight, which would push the reading several degrees above the actual air temperature.
💧 Humidity, the other half of the climate
Relative humidity matters as much as temperature in a closed greenhouse. Too low, and it dries out young seedlings and cuttings, which lose water through their leaves before they have roots. Too high and without ventilation, it encourages condensation on the walls and foliage diseases: above 85% relative humidity, with still air and wet leaves, grey mould finds the conditions it likes. The hygrometer tells you when to open the vents or, on the contrary, keep the lid of a propagator closed, as explained in the guide to setting up your seedling area. As the device is accurate to within 5%, aim for 80% at most to keep a margin below this threshold.
🌙 The readings that matter
The time of day at which you take a reading greatly changes what it tells you. The morning reading, just before opening up, gives the lowest temperature and highest humidity of the day, because the greenhouse air cools overnight and its vapour approaches saturation. On a clear night, the leaves and glazing cool even faster than the air, so dew forms on them while the display still shows a humidity below 100%. The afternoon reading, by contrast, flags the heat spikes that make lettuces bolt. The memory on the Premium version saves you from getting up at dawn to find out the night-time temperature, and two readings noted each day are enough to set your ventilation and heating.
🐟 The air above the tank
In an aquaponic greenhouse, the device measures the air above the crops, and this air is almost always more humid than that of a conventional greenhouse, since the water in the tank evaporates day and night. When the hygrometer stays above 80% in the morning, renew the air: an oscillating fan circulates the air around the leaves, and a ducted extraction, tempered in winter by a duct heater, removes the vapour without chilling the crops. The air temperature tells you nothing about that of the water, which changes more slowly and governs the activity of the fish and bacteria, at 10 to 18 °C for salmonids and 22 to 32 °C for warm-water fish: it is monitored separately, every day, with a suction-cup thermometer fixed in the tank. Finally, keep the probe out of the water, as it measures the air and is not designed to be submerged.
Technical specifications
The measurement
- Parameters
- Temperature and relative humidity
- Range in Premium
- 0 to 50 °C, 25 to 90%Accuracy of 1 °C and 5% humidity
- Remote probe
- Medium and Premium1.5 m cable on the Premium, air measurement only
- Memory
- Temperature logging with PremiumTo find out the temperature reached overnight
The housing
- Screen
- LCD from 5 x 5 to 6.5 x 7.5 cmMedium and Premium
- Dimensions
- 12.5 x 6.5 x 1.7 cm in Medium12 x 9 x 2.5 cm in Premium
- Feeding
- 1 AAA battery includedMedium and Premium
- Fitting
- Wall-mounted or flatIn the shade, at plant height
In the box
- 1 Garden HighPro digital thermo-hygrometer in the version of your choice
- 1 AAA battery, in the Medium or Premium version
- 1 remote probe, in Medium or Premium version
Manufacturer's values for the Medium and Premium versions. 85% humidity threshold according to Ohio State University.
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Frequently asked questions
6 questions
6 key questions
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