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Humidity refers to the amount of water vapor in the air, typically measured as relative humidity (RH)—the percentage of water vapor present compared to the maximum it can hold at a specific temperature. RH is influenced by two factors: the amount of water vapor and the air temperature. For cannabis growers, understanding these factors is essential to maintaining an optimal environment and preventing humidity-related issues.

Effective humidity control is crucial for preventing Botrytis, commonly known as bud rot—a fungal disease that thrives in high-humidity environments. Due to the dense structure of cannabis buds, they easily trap moisture. As the plant transpires and releases moisture, this creates ideal conditions for mold development.

The key to preventing bud rot is controlling humidity levels. While humidity itself is just water vapor, the real issue arises when water condenses into liquid, which can happen directly on the plant. As cannabis plants transpire to regulate their temperature, they cool down, causing moisture to condense inside the buds, which can lead to mold growth. To manage this, growers must understand the dew point and how it influences condensation.

The dew point is the temperature at which air becomes saturated with water vapor, causing the vapor to condense into liquid water. Simply put, it's the point where water droplets begin to form because the air can no longer hold all the moisture.

Think of a cold glass of water on a warm day. As the glass temperature drops below the dew point, water forms on its surface. The same happens in a cannabis growing environment when humidity condenses on cooler surfaces like walls, ceilings, or even the plants themselves.

Temperature and RH are closely connected. Imagine the air as a sponge—it can only absorb a certain amount of water before becoming saturated. If the temperature drops or humidity rises, the air reaches its saturation point, and any excess moisture condenses as liquid. This means that by reducing RH or increasing temperature, you can prevent condensation.

However, fluctuations in temperature also affect RH. Warmer air holds more water, so as the temperature rises, RH decreases, reducing the chance of condensation. Managing both temperature and humidity is essential for controlling the dew point, and tools like DryGair’s dehumidification systems can help growers maintain that balance.

To effectively manage condensation, growers need to understand the dew point in their facility. The following graph represents the dew point as a function of RH at a given air temperature:

This graph represents 70% RH. You can notice that at an air temperature of 70°F (bottom axis), the graph aligns with 60°F dew point temperature (left axis). This means that if your greenhouse air is at 70% RH with an air temperature of 70°F, the dew point would be around 60°F. If any surface—such as walls, ceilings, or pipes—drops to 60°F or lower, water will condense on it. This is especially problematic for the plants themselves, which tend to cool down and act as surfaces for condensation.

A knowledge-based approach to climate control helps growers optimize growing conditions at minimal cost. By understanding the dew point and its influencing factors, you can make informed decisions about when to heat or cool your growing environment. It’s not just about maintaining a specific temperature—it’s about balancing temperature and humidity to protect your crops from moisture-related issues.

DryGair’s dehumidification solutions are designed to help cannabis growers manage the dew point effectively. By preventing condensation, DryGair ensures that your crops are safe from the risks associated with high humidity, while also reducing energy consumption and improving overall climate control.

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