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Growing plants, whether in the garden or in the greenhouse, requires a deep understanding of the factors that influence plant growth and health. One of the crucial variables that gardeners and plant growers should consider is the VPD (Vapor Pressure Deficit) value. In this blog post we will look at VPD levels, how they affect plant growth and how you can create optimal conditions for growing plants.
What is VPD and why is it important?
VPD, or Vapor Pressure Deficit, is a measure of the difference between the actual water vapour pressure in the air and the maximum possible water vapour pressure at a given temperature. In simpler terms, VPD indicates how dry or humid the air is in relation to the current temperature.
VPD is important because it has a direct influence on the ability of plants to absorb and evaporate water through their leaves, a process called transpiration. Transpiration plays an important role in the uptake of nutrients, the cooling of plants and the regulation of water balance. An optimal VPD value promotes healthy plant growth, while unfavourable VPD values can lead to a number of problems, such as wilting, reduced nutrient uptake and susceptibility to diseases.
Optimal VPD values for plant breeding
For most plants, the optimal VPD value is between 0.8 and 1.2 kPa (kilopascals). In this range, plants can transpire effectively, allowing them to take up the nutrients they need and regulate their internal temperature. However, it is important to note that different plant species may have different VPD requirements. Therefore, you should be aware of the specific needs of the plants you are growing.
How to control and optimise VPD values
To achieve optimal VPD levels in your grow room or greenhouse, you need to monitor and control both temperature and humidity. Here are some steps you can take to optimise VPD levels:
- Temperature monitoring and control: Make sure you use a reliable thermometer to monitor the temperature in your grow room or greenhouse. To regulate the temperature, you can use heaters, fans or air conditioners, depending on your needs.
- Humidity monitoring and control: Use a hygrometer to monitor the humidity in your grow room or greenhouse. To increase the humidity you can use a humidifier and to decrease it you can use a dehumidifier or good ventilation.
- VPD calculation: To calculate the VPD value, you need the temperature and the relative humidity (RH). There are online VPD calculators or apps that will do the calculation for you. This way you can ensure that you maintain the optimal VPD values for your plants.
- Adaptation to plant development: Take into account that the optimal VPD values may vary during the different growth phases of a plant. As a rule, plants prefer a higher VPD value during the vegetation phase, while they prefer a lower value during the flowering and fruiting phase. Be sure to adjust VPD levels according to the stage of development of your plants.
Other factors for successful plant breeding
In addition to controlling VPD levels, there are other important factors you should consider when growing plants:
- Light: Make sure your plants get enough light, be it natural sunlight or artificial lighting. Light quality and intensity are crucial for plant growth and photosynthesis.
- Nutrients: Make sure you give your plants the right amount of nutrients and fertilisers. Over- or under-fertilisation can lead to growth problems, diseases and lower crop quality.
- Watering: Watering is another crucial factor for plant growth. Be careful not to over- or under-water your plants. The optimal amount of water depends on the plant species, growth stage and environmental conditions.
- Pest and disease control: Regularly monitor your plants for pests and diseases. Take early action to prevent or contain outbreaks by using biological, chemical or cultural control methods.
Considering VPD levels when growing plants can make a significant difference to the growth and health of your plants. By monitoring and controlling temperature, humidity and VPD, as well as considering other important factors such as light, nutrients, watering and pest and disease control, you can create optimal conditions for growing plants. By considering the specific needs of your plant species and adjusting the environmental conditions during the different growth stages, you will promote healthy and vigorous growth and ultimately maximise your crop yields and quality. Successful plant growing requires patience, care and constant learning, but the rewards are worth the effort.