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Greenhouse Ventilation & Cooling

Selecting Your Greenhouse

  • Greenhouse Ventilation & Cooling

    Greenhouse gardening allows you to maintain an even or optimum growing environment for your plants. One way to accomplish that is by offering greenhouse ventilation and cooling assistance during the warm, summer months.
     
    ROOF AND SIDE GREENHOUSE VENTING
    • Roof venting is still considered the best of greenhouse ventilation systems.  A roof vent serves as an escape route, but it also provides a source of cool air intake.
    • Individually controlled roof vents in the greenhouse allow the intake of cool air to be a gentle flow to bench level, not a strong force that suddenly lowers the temperature.
    • Glass louvers or hinged side venting is also very common at the bench level or lower. Side venting will certainly assist in cooling the greenhouse in the warmer seasons.

    GREENHOUSE SHADING
    • During the spring and summer, direct sunlight can quickly overheat the greenhouse and destroy both plants and seedlings.
    • Exterior shading is the most effective method of preventing heat build-up.Shade cloth, or screening material, has been used by commercial growers for many years and is now available for hobby greenhouses.
    • Higher density shade cloth is more suitable for orchids or other tropicals.

    GREENHOUSE AUTOMATIC VENT OPENERS
    • Automatic vent openers are self-contained units which require no electricity.
    • On a sunny day, heat will build up around the cylinder mechanism, and the vent will slowly start to open. Similarly, as the air cools around the cylinder the vent will close.

    Greenhouse Automatic Vent Opener

    GREENHOUSE EXHAUST FANS
    • Will a greenhouse require an exhaust fan? This depends on the type of venting system that is built into the greenhouse structure, and if there is shading on the exterior of the greenhouse.
    • Specialty greenhouses for orchids, chrysanthemums, or tropicals, require exhaust fans to maintain a controlled environment.
    • The ideal requirement for air exchange in the greenhouse is one complete air exchange per minute.

    Greenhouse Exhaust Fan

    GREENHOUSE AIR CIRCULATION
    • To equalize the temperature and distribute air evenly within the greenhouse, one should ensure constant air circulation.
    • Condensation can be greatly reduced if there is constant air circulation. For the best results, it is recommended that one install a small circulating fan to maintain a continuous movement of air.

    Greenhouse Air Circulation Fan

    SHADE CLOTH 
    • The best way to provide cool shade and protect plants from sunburn is with a fabric shade cloth designed for use outside of the greenhouse.  
    • The exterior shade cloth should sit a few inches above the greenhouse glazing.  Do not lay the shade cloth directly on top of the greenhouse glazing.  An exterior shade cloth is 40% more effective than an interior shade cloth.