Protected cropping explained

Protected cropping involves using structures and technologies to create a controlled environment in which to grow crops. One example of protected cropping is organic greenhouse production. Thereby, plants are cultivated in a controlled environment. Factors such as temperature, humidity, light and water can be managed to support plant health and productivity.

Controlled environments can extend the growing season, reduce pest pressure naturally, and improve yield and quality. The level of technology and investment determines the type of structure used to achieve a desired degree of environmental control.

The four main types of protected cropping (low tunnels, plastic tunnels, polyhouses, glasshouses) used in organic greenhouse production are outlined below:

Low tunnels

Low tunnels are simple and affordable structures consisting of hoops covered with clear plastic film and placed directly above the crop rows. They protect crops from wind, frost and heavy rainfall and raise soil and air temperatures during cooler months. Although they are not climate-controlled, they create a microclimate that is beneficial for the early and extended production of crops, particularly leafy greens and herbs, in organic systems.

Drei Folientunnels stehen nebeneinander. — Plastic tunnels are a type of protected cropping. (Photo: FiBL, Thomas Alföldi)

Plastic tunnels

Plastic tunnels, also known as walk-in tunnels, are semi-permanent structures that offer more headroom and ventilation than low tunnels. Constructed with a steel frame and polyethylene cover, they are easy to build and maintain. These tunnels enable better airflow and can support trellised crops such as tomatoes or cucumbers. Although they are still low-tech, they offer good protection from pests and weather while maintaining organic farming principles.

Plants are growing inside a polyhouse which is a type of protected cropping. — Research trials are being conducted in the FiBL polyhouse at the Frick site. (Photo: FiBL, Mica Ludek)

Polyhouses

Polyhouses are large, high-tech greenhouses covered with UV-stabilised plastic film. They offer a much higher level of environmental control thanks to features such as drip irrigation, passive or active ventilation and shading systems. In organic production, they enable the intensive cultivation of high-value crops year-round while conserving water and nutrients. Polyhouses are ideal for producers seeking higher yields and better crop quality without the use of chemicals.

Ein Gewächshaus mit geöffneten Türen steht vor einem Hügel. — Glasshouses allow highest control of growth conditions. (Photo: FiBL, Thomas Alföldi)

Glasshouses

Glasshouses are state-of-the-art facilities offering full control over the growing environment, including temperature, light, humidity and CO₂ levels. Built with glass panels and automated systems, they enable precise organic crop management under stable conditions. Although they are the most expensive option to build and operate, glasshouses are ideal for organic producers targeting premium markets and looking to supply produce consistently throughout the year.