Climate control is an integral part of modern cultivation. These systems are found in greenhouses, indoor growing spaces, hydroponic agriculture, vertical farms and more. In most cases, this includes humidity control and air circulation, which drastically reduce disease outbreaks and crop loss.
But besides combating humidity diseases such as downy mildew or bud rot, do greenhouse humidity control systems and air circulation improve plant growth? The short answer is – absolutely.
Humidity control, nutrient transport and plant growth
Plant growth is determined largely by the amount of nutrients a plant absorbs. These nutrients are found in the soil or growing solution. When plants uptake water through their roots, they receive these essential materials.
As the nutrient-rich water is transported through the plant, the different nutrients are absorbed where they’re needed. The excess water is eventually evaporated through the leaves.
The transpiration of water vapor, from the leaves, creates the force that sucks in water through the roots. This is called the xylem pull. The faster the transpiration – the faster water and nutrients are taken in. When evaporation slows down, or ceases, so does the water uptake.
This is where humidity intersects with plant growth. The transpiration from the leaves is directly affected by humidity. When relative humidity is high – meaning there is a lot of water vapor already present in the air, the rate of water evaporation slows down. This can also be described as low VPD (vapor pressure deficit). When the air is relatively dry, meaning VPD is high, the rate of transpiration goes up.
Many modern greenhouses adhere to the practice of plant empowerment, often referred to as next-generation growing. This cultivation theory emphasizes the optimization of plant growth. A major part of plant empowerment is greenhouse climate control, specifically humidity control.
Each plant has its own ideal VPD level at which it grows fastest, healthiest and at the highest quality. For most crops, this range is between 0.8 kPa and 1.2 kPa.
By assuring the relative humidity levels are within optimal range, growers can help ensure their crops maximize their potential.
Air circulation completes climate control efforts
Greenhouses are dynamic environments. While we attempt to evenly control the climate throughout the entire space, the plants themselves constantly change their immediate surroundings.
As plants transpire, the area around them becomes humid. This is called the boundary layer. When plants are placed densely, or their foliage grows too lush, the boundary layer becomes trapped, causing pockets of humidity to form.
These pockets, or microclimates, are usually dealt with by increasing the dehumidification efforts. But dehumidifiers alone aren’t always able to reach these small air pockets, leading to overuse and unnecessary energy expenses.
This is where air circulation comes in. Properly designed circulation is meant to homogenize the climate in the space. It achieves this by effectively sending air in all directions, to all corners of the greenhouse. This way, the boundary layers are quickly dispersed, even inside the canopy.
By eliminating microclimates, the entire growing space essentially experiences one uniform climate. This makes climate control much more effective, increasing the rate of growth and quality of the crops, while decreasing unnecessary energy consumption.