Greenhouse Temperature Control Best Practices
Crops grown in controlled environments allow us to produce more and higher-quality produce all year. This principle underpins and sustains modern horticulture. Climate control is one of the most important aspects of growing in a protected environment, such as a greenhouse.
Growers get the best of both worlds by growing in a greenhouse. They can use natural sunlight while still protecting their plants from the elements. However, to get the most out of greenhouse growth, growers must effectively control the conditions inside.
Improving growing conditions and gaining control of the growing process are critical components of plant empowerment, which is an integrated cultivation approach that prioritizes the plant and seeks to maximize plant growth and health.
Improving climate control in your greenhouse aids in disease prevention, plant growth, quality, and energy savings.
Temperature Control in Greenhouses
Every plant has an ideal temperature range. They perform photosynthesis and other metabolic processes within this range as efficiently and quickly as possible. This is the most fundamental aspect of greenhouse climate control and was most likely one of the driving forces behind the invention of the first greenhouses.
Providing cover does not guarantee ideal temperatures. Most growers heat or cool the air to achieve their perfect temperature range. The need for heating or cooling varies depending on the climate, geography, crop type, etc.
How to Regulate Greenhouse Temperature
There are numerous greenhouse heating methods, including ground heating, table heating, heat pipes, and others. Many modern greenhouses use CHP (combined heat and power) systems to reduce energy costs and increase efficiency.
Thermal screens are another popular solution. Screens aid in trapping heat within the greenhouse, reducing the need for additional heating. They're an excellent addition to any greenhouse that requires frequent heating.
Greenhouses can be found in all climates around the world. As a result, some people will inevitably require cooling rather than heating. Air conditioning, or HVAC, which can also heat, or wet pads and fans are standard cooling options.
Temperature and humidity are inextricably linked, so how you heat or cool should always consider humidity, and vice versa.
Humidity Control in Greenhouses
Plants, like humans, have an ideal relative humidity range. The proper humidity level allows plants to metabolize, develop, and bear fruit while remaining healthy, strong, and vibrant.
Dry Weather - Low Relative Humidity
When conditions are too dry, plants will transpire excessively, causing water stress. This is a physiological state in which the plant slows or stops critical processes to conserve water.
If the air in your greenhouse is too dry, you can use misting systems or wet pads to introduce more water vapor and increase humidity.
High Relative Humidity Conditions
However, dry weather is much less common. Most greenhouses have excessively high humidity levels. This is because plants constantly transpire. More than 90% of the water they absorb via their roots is evaporated via the leaves' stomata.
The air can become saturated with water vapor when humidity levels are excessively high. The dew point is when relative humidity reaches 100%. Perspiration becomes physically impossible under these conditions. The air simply cannot accommodate any more water.
Transpiration is an essential component of the plant's nutrient transport system. As a result, extremely high humidity similar to water stress. Because it cannot transport water, the plant is forced to slow down its metabolic processes.
Disease and mildew outbreaks are other major issues caused by high humidity. Downy mildew and gray mold, for example, require high humidity to grow. Once they do, however, it is challenging to stop their spread, even if humidity levels return to normal. Toxic fungicides, which are unhealthy to consume in food and are prohibited from use in regulated medicinal crops like cannabis, are the only way to stop the spread of molds once they have broken out.
Controlling Greenhouse Humidity
Ventilation is the traditional method of dealing with greenhouse humidity. When the weather permits, ventilation can be highly beneficial. The issue is that the outside conditions are only sometimes favorable. When it's raining, humid, or too cold outside, ventilation may not help at all. Most of the time, this happens overnight.
However, even if ventilation reduces humidity, it can be inefficient and costly. This is due to the release of greenhouse air, which already contains energy in the form of heat. Growers must keep constantly heating when releasing hot air and introducing cold air to maintain ideal temperatures, which comes at a high cost.
Dehumidification is the most comprehensive solution to high humidity. Dehumidifiers use controlled condensation to physically remove water vapor from the air. Dehumidifiers effectively and efficiently reduce humidity in this manner.
Controlling Greenhouse Gases and Lighting
The third factor growers can influence in their greenhouses is lighting or radiation. This is a critical factor in the survival of plant life. The amount of radiation has a direct impact on the ability of plants to photosynthesize, develop, and grow.
While growing in a greenhouse may provide free sunlight, this is not always the case. In many climates, sunlight is not as consistent as growers would like. In these conditions, greenhouses frequently use supplemental grow lights to provide light when it is cloudy or foggy or to lengthen the day.
Some plants, such as cannabis, produce flowers and fruit at different times of day and night. This is known as photoperiodism. Growers must accommodate the lighting requirements of these plants in order for them to grow optimally. This could include up to 24 hours of intense light per day!
Photoperiodic plants, on the other hand, may require extended periods of complete darkness. This cannot be provided naturally in most places. As a result, many cannabis growers use blackout screens to extend the dark period, or even during the night, in order to reduce light exposure as much as possible.
It is important to note that radiation, including both visible and non-visible radiation such as UV, has a significant impact on temperature and humidity. Radiation raises the temperature, but it also raises the transpiration rates of plants, resulting in higher humidity.
Creating ideal growing conditions in a greenhouse is a delicate balance. It necessitates a thorough understanding of greenhouse physics, as well as constant tweaking and optimization of growing protocols.
Managing Greenhouse CO2 Emissions
The three most important aspects of greenhouse climate control are temperature, humidity, and radiation. Growers can achieve incredible results simply by focusing on the balance of the three.
However, greenhouse operators can go a step further and enrich their greenhouse environment with additional CO2. CO2 is an important material required for photosynthesis and plant assimilation, which means it helps the plant produce the compounds it requires to grow.
CO2 enrichment of the air can help plants grow faster. However, it, too, must be balanced. Plants may require additional lighting to benefit from the metabolic boost provided by CO2. As previously stated, increased light may raise temperature and humidity, which growers must consider.
Changing any of these four elements has an impact on the others. Greenhouse growers must walk a fine line in order to constantly manage all climate parameters.
Greenhouse Climate Control Monitoring and Automation
The best way to ensure ideal greenhouse conditions at all times is to install proper monitoring devices.
It is critical to spread out multiple monitoring devices in order to get a true picture of what is going on in the greenhouse.
Growers, for example, should use multiple thermostats located in different parts of the greenhouse to get a realistic temperature reading. The same can be said of humidity monitoring equipment.
One of the most serious issues in greenhouses is a lack of climate uniformity. As a result, one area may be dry while another is extremely humid. As a result, some plants may grow faster than others.
Worse, inhomogeneous conditions promote disease development, which can easily spread and infect the remaining plants, even if their local conditions are ideal.
Monitoring the dehumidifier's water extraction is another way to ensure proper water balance. Growers can easily determine if they are removing enough water by comparing extracted water to irrigation.
Once a grower has a proper monitoring system in place that provides accurate information on greenhouse conditions, they can begin automating certain processes.
DryGair dehumidifiers, for example, connect to the monitoring system and can be set to begin dehumidifying only when relative humidity reaches a certain threshold. Heating and cooling, lighting, and even CO2 enrichment can all be done in the same way.
Monitoring and automation can mean the difference between a profitable and a failing greenhouse. It has the potential to transform a low-output greenhouse plagued by diseases and high production costs into an efficient greenhouse producing large, high-quality yields.
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