A hoop house is a structure designed to create a protected microclimate for growing crops. This straightforward, plastic-covered framework is an unheated, passive solar structure that allows growers to extend the natural growing season. Its primary purpose is to shield plants from adverse weather conditions while harnessing the sun’s energy to promote earlier planting and later harvesting. This low-tech design increases crop productivity without the high energy costs of a fully heated facility.
Core Structure and Materials
The physical design of a hoop house is defined by its arched frame, which gives the structure its name. The framework is typically constructed from continuous, bent materials like galvanized steel conduit or specialized PVC piping. These curved supports are spaced at regular intervals, usually every four to six feet, and are anchored to the ground or secured to wooden baseboards for stability.
The structure is covered with a single layer of specialized polyethylene film, often referred to as poly-film, which serves as the protective skin. This plastic sheeting is engineered to be UV-resistant and is commonly between 4 and 8 millimeters (mil) thick to ensure durability. The film is tightly secured to the frame using specialized clips, battens, or channels to create a sealed environment that traps solar energy.
Hoop houses are considered semi-permanent structures because they lack a traditional foundation and can be disassembled or relocated. The simplicity of the material list, relying on readily available piping and plastic, makes them a cost-effective alternative for protected cultivation.
Primary Function and Use
The operational success of a hoop house relies on passive solar heating, often called the greenhouse effect. The clear poly-film covering permits short-wave solar radiation to enter the structure, where it is absorbed by the soil, plants, and interior air. This energy is re-radiated as long-wave infrared heat, which is then trapped inside by the plastic covering, significantly warming the internal environment.
This modification provides two primary benefits: protection and season extension. By raising the internal air and soil temperature, a hoop house enables gardeners to start seedlings weeks before the last expected spring frost. Similarly, the retained heat allows for continuous production of cold-hardy crops well past the first fall frost.
The enclosed environment also shields crops from damaging elements like heavy rain, strong winds, and hail. However, trapped heat necessitates active management, especially on sunny days. Growers must incorporate ventilation, often by rolling up the sides or opening end-wall doors, to prevent internal temperatures from damaging the plants.
How It Differs From a Traditional Greenhouse
The distinction between a hoop house and a traditional greenhouse centers on their structural complexity and method of temperature control. Traditional greenhouses are engineered structures built with permanent foundations, glass or rigid polycarbonate panels. In contrast, the hoop house is a lighter, less complex structure that is semi-permanent and can be moved.
A core difference lies in their approach to heating and energy use. A hoop house relies exclusively on passive solar heat gain and the thermal mass of the soil. Greenhouses, however, are often equipped with active heating, cooling, and ventilation systems, including furnaces, which allow for a higher degree of environmental control. This active climate management makes the greenhouse significantly more expensive to operate.
Greenhouses are generally designed for year-round production of a wide variety of crops, often utilizing benches or hydroponic systems. Hoop houses are primarily used for season extension, covering crops grown directly in the ground. They are less suited for maintaining tropical temperatures throughout a harsh winter. The simplicity of the hoop house design makes it substantially less expensive to construct, typically costing only a fraction of the expense required for a permanent, engineered greenhouse.