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How to adjust your cultivation using a plant temperature meter

temprature meter
Written by René Mondt | Last update 28-06-2020

Temperature is a very important factor for the growth of a crop, it influences the speed at which a plant develops. This is why every grower also measures the air temperature in his greenhouse. The plant temperature could however be 4°C lower or 6°C higher than the air temperature. Measuring only the air temperature, you won’t gain insight in this temperature difference, due to which you cannot adequately respond. It is therefore recommended to measure the plant temperature by means of a plant temperature meter (PT-meter). This will help you to follow and adjust the development of the crop.

Causes of temperature difference

The difference between the air temperature and the plant temperature can be caused by different factors. These may be sunlight, cold outside air and the heat radiation of pipes in the greenhouse, but could also emerge in the event of high irradiance, low humidity or a lot of radiation.

Evaporation pressure (VDP)

In addition to insight in the plant temperature, a plant temperature meter also offers insight in the evaporation pressure (VDP). This is the difference the evaporation pressure in the stomata of leaves and the evaporation pressure in the greenhouse. This can be used to determine the potential evaporation of a plant (please note: this is not possible for the relative humidity or moisture loss).

Optimal growth

By measuring the plant temperature and the evaporation pressure of a plant, you can prevent overheating and condensation of plants, flowers and/or fruits, when timely adjusting the climate conditions in the greenhouse. This will ensure optimal growth with less energy consumption and it reduces the risk of fungus formation in the crop.

Connecting to a climate computer

A plant temperature meter can be connected to the climate computer. The advantage here is that the climate computer can immediately automatically adjust values (like heating, ventilation, shielding and air humidification), on the basis of the measured plant temperature. This quick shifting ensures that the crop’s needs will be met as soon as possible. In addition it helps to save on unnecessary loss of energy, CO2 and moist.

Placing a plant temperature meter

When placing one or more plant temperature meters, you should consider a number of issues:
  • Mount the camera at 60 centimeters above the growing tips of the crop. When the crop has grown and there is only 40 centimeters left between the camera and the growth tips, then raise the camera by 20 centimeters.
  • Always point the camera away from the sun (between north-west and north-east) and preferably transversely to the plant rows.
  • Make sure that there are no objects between the lens and the crop, this will disrupt the measurements. When looking through the round openings below the camera, you will see about the same as the camera does. If there anything within the view, move it. If this is impossible, then mount the camera in another location.

Maintenance of plant temperature meter

When the camera – the lens in particular – is polluted, this may influence the measuring results. Therefore, you should check the camera on pollution every three months and clean it if necessary. Dust can simply be removed by means of pressurized air. Tough dirt can be removed with a tissue or cotton cloth with alcohol or methylated spirit. Never use aggressive detergents or scouring agents; this will damage the device!

In addition, always shield the lens of the camera when applying crop protection agents in the greenhouse. To do this, use the included plastic protective cover cap. If you clean the greenhouse using aggressive detergents, then shield the entire device to prevent damage.

Calibrating the plant temperature

Furthermore, have the plant temperature calibrated every three years, by a certified technician. Over time, measuring errors may arise, resulting in incorrect measurements. By having the device calibrated, you can solve this problem.

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Questions about plant temperature meter

Do you have a question about the usage of a plant temperature meter, or would you like customized advice? Then contact one of our product specialists, or ask your question via below form. We will then contact you as soon as possible, even within 24 hours on working days.

Rene MondtAbout René Mondt

René Mondt, product specialist for measuring equipment and technique, was born in the greenhouse environment and has been working in the horticulture sector, being rather experienced with the technical part of the cultivation. He understands the customer and cultivation like no other. "My motto is to assist the customers and support them the way I would prefer to be supported myself: quick and tailor-made advice."

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