Excess humidity in greenhouses fuels mold and plant disease. It can ruin crops and drive up energy costs. For greenhouse managers, controlling moisture is a constant challenge. Traditional ventilation helps but often falls short—especially in large, hydroponic, or fully enclosed growing setups. Below, we explore the humidity problem and how industrial dehumidifiers address it across different greenhouse environments.
Greenhouse Humidity Challenges
Causes of High Humidity in Greenhouses
Greenhouses create a closed environment to retain heat, but this also traps moisture. Plants constantly release water vapor through transpiration, and irrigation systems add more humidity to the air. During daytime, warm air holds a lot of moisture. When the temperature drops at night, that moisture condenses on cooler surfaces as droplets. With vents closed to preserve heat, humidity builds up overnight. In hydroponic and dense planting setups, open water surfaces and abundant foliage further raise the moisture level. Limited airflow or insufficient ventilation means the excess water vapor has nowhere to escape.
Consequences of Uncontrolled Humidity
Persistently high humidity in a greenhouse leads to several serious problems. It creates an ideal breeding ground for fungal diseases like powdery mildew and Botrytis, which can spread quickly and devastate crops. Leaves stay wet longer, inviting rot and bacterial infections. Extremely moist air can also interfere with plant processes – for example, plants may have trouble absorbing nutrients when humidity is too high, resulting in weaker growth. Condensation dripping from the ceiling can damage flowers or fruits and spread pathogens. To counteract high humidity, growers often resort to extra ventilation or heating, but this drives up energy use. In fact, unchecked humidity can put crops at risk of yield loss and force growers to spend more on climate control.
Benefits of Industrial Dehumidifiers for Greenhouse Growth
Prevents Diseases and Rot: Using dehumidifiers to keep relative humidity in a safe range makes it much harder for diseases like powdery mildew, Botrytis, and downy mildew to take hold. Drier foliage means fewer spores germinating and less risk of rot on leaves, fruits, and flowers.
Boosts Plant Growth and Yield: When moisture is balanced, plants can breathe and transpire normally. This means they uptake water and nutrients efficiently, fueling steady development. Crops grow faster, fuller, and with fewer stress-related issues.
Stabilizes the Growing Climate: Industrial dehumidifiers help create a more consistent greenhouse climate day and night. A controlled environment leads to uniform growth across the greenhouse — every plant receives similar conditions. It also reduces the need for emergency interventions to correct humidity, simplifying greenhouse management.
Designed for Greenhouse Conditions: Industrial greenhouse dehumidifiers often have high removal capacities to match a greenhouse’s moisture load. Many are equipped with humidistats and digital controls, so growers can set a desired humidity level and the unit will automatically cycle on or off to maintain that target. They can be installed as standalone units or integrated into the greenhouse’s climate control system. The water pulled from the air is usually drained via hoses; growers often reuse this distilled water for irrigation. With industrial dehumidifiers in place, humidity can be controlled precisely around the clock—something passive methods cannot achieve.
Energy Efficiency and Cost Savings: Industrial dehumidifiers improve greenhouse energy efficiency by reducing the need for constant ventilation and heating. By recirculating warm air while removing moisture, they prevent heat loss. The electricity that dehumidifiers do use largely turns into heat during the drying process, and that heat stays in the greenhouse. Growers can lower heating fuel use and electricity bills, often cutting climate control energy costs by a significant margin.
Selecting the Right Industrial Dehumidifier
When choosing a dehumidifier, growers should weigh several key factors:
Greenhouse volume: A greater air volume requires a dehumidifier with a higher moisture removal capacity. Manufacturers rate dehumidifiers by how many pints or liters of water they can remove per day – use your greenhouse’s size to estimate the capacity needed.
Type: Beyond capacity, consider the physical type of dehumidifier best suited for your space. Growers can typically choose between floor-standing dehumidifiers and ceiling-mounted dehumidifiers. Ceiling-mounted units are an excellent choice for maximizing usable floor space, as they do not occupy valuable ground area.
Humidity sources: Consider how much water is added to your air daily. High-density planting, frequent irrigation, misting systems, or hydroponic nutrient tanks all increase humidity. More moisture input means you’ll need a stronger dehumidifier to keep up.
Climate conditions: A greenhouse in a naturally humid climate or rainy region will face a heavier constant humidity load than one in a dry climate. In humid locales, choose a more robust unit or multiple units. In drier areas, a smaller unit may suffice except during watering cycles.
Integration and placement: Determine whether you need one large centralized dehumidifier or multiple smaller units placed around the greenhouse for even coverage. Also plan where the unit will drain water and ensure airflow from the unit will reach all corners of the space.
Application of dehumidifiers in different types of greenhouses
Different greenhouse setups may require different dehumidifier approaches. The table below highlights considerations for various greenhouse types:
| Greenhouse Type | Humidity Challenges | Recommended Dehumidifier Solution |
| Commercial (Large) | Very large volumes and dense crops create heavy moisture buildup and condensation. | Use high-capacity industrial units (often ducted or central systems) to cover the entire area. Integrate them with the climate control system for uniform humidity and temperature. |
| Hydroponic Systems | Open water tanks and constant evaporation lead to extremely high humidity. | Deploy high-extraction dehumidifiers that can run continuously. Ensure units are corrosion-resistant and can handle 24/7 operation to keep up with moisture generation. |
| Vertical Farms (Indoor) | Enclosed, multi-level growing spaces trap moisture and heat across tiers. | Use precise-control dehumidifiers integrated with the HVAC system. Often multiple smaller units or a distributed system is needed to maintain even humidity on every level. |
| Small-Scale Greenhouses | Smaller volume spaces still experience humidity swings from watering and temperature changes. | Choose a compact industrial-grade dehumidifier sized to the space. A portable unit with an automatic humidistat is usually sufficient and cost-effective for hobby or small commercial greenhouses. |
FAQ
Q: What is the ideal humidity level for a greenhouse?
A: Most plants thrive around 50% to 70% relative humidity in a greenhouse. It can vary by species, but generally keeping humidity under about 80% helps prevent fungal issues.
Q: How do I choose the right dehumidifier for my greenhouse?
A: Measure your greenhouse’s size and estimate how much moisture your plants add. Pick a unit rated to remove at least that amount, and opt for one with an automatic humidistat.
Q: Are greenhouse dehumidifiers energy efficient to run?
A: Yes. Dehumidifiers use electricity, but they’re efficient. They remove moisture without losing heat, so you usually save more in heating costs than the electricity the dehumidifier consumes.
