Bedding plants are commonly grown in greenhouses equipped with environmental controls used to manage and manipulate temperature, humidity, and light. While not all greenhouses may be outfitted with horticultural lights, most if not all contain heaters and exhaust fans utilized to heat and cool the growing environment. Advantages of heating and cooling the growing environment allow growers to control the rate of crop development, such as leaf unfolding or the progression toward flowering. Behind labor, fuels for heating and utilities (lighting, ventilation, and water) to control greenhouses can lead to substantial operating costs.
Many growers have begun utilizing high tunnels or modified haygroves as alternative production environments for growing bedding plants to reduce heating and utility costs and offset carbon emissions and water usage. A high tunnel can best be described as a semi-controlled environment because the structure is typically glazed with a single layer of polyethylene providing protection from outdoor climatic conditions, and lacks a heater and exhaust and horizontal airflow fans.
High tunnels are heated by solar radiation and cooled by passive ventilation through the side and/or end walls that are manually opened by growers or with handheld power tools. In some instances, growers can install solar-powered ventilators and/or motorized crank systems that can raise and lower the sidewalls. Previous research has shown that growers can utilize high tunnels and low-cost technologies to reduce or eliminate heating costs associated with bedding plant production.
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