Season Extension and Increased Economic Sustainability for South Florida Growers: Using high tunnels to extend tomato production

Sustainability in farmer practices emphasizes not just the inputs and methods of growing and how they impact harvest outcomes, but also economic and social sustainability of food systems. Reflecting this, there has been movement over the past several years to increase the availability of local produce and food products in both an effort to support local economies, as well as decrease the environmental burden of transporting food products around the world. At the same time, consumers have come to expect a reliable, year-round source of a variety of produce. Local food systems, then, must develop and implement sustainable methods to extend the growing season to meet market demand.

For vegetable growers in the Southern United States, particularly those in the sub-tropical climate of south Florida, season extension runs into several challenges unique to the climate. Production is highest during the winter months due to milder, drier weather. During the other half of the year, production dwindles as the summer months approach. Heat, humidity, and high amounts of rainfall contribute to the difficulty of growing during summer months. In particular, these environmental conditions contribute to significant pest pressure and susceptibility for disease which, in turn, cause significant challenges for growers using organic, sustainable practices.

Most vegetable growers in south Florida start their growing seasons in September, selling their first produce in early November. These growers often have to end their season in April, losing out on income for a significant portion of the year and contributing to growers’ economic insecurity during this time. This growing pattern hits small growers and urban growers particularly hard, as profit margins are small due to the capacity of growers and the high price placed on land in urban and sub-urban areas. Season extension would offer these growers a means of increasing their economic sustainability by maximizing the time they are able to grow and sell their crops. At the same time, availability of local produce for a greater portion of the year would help increase market demand for local produce, increasing both economic sustainability of local growing practices, as well as having the improved environmental sustainability that comes from sourcing produce from local growers.

Many season extension methods have been used effectively across the country. For much of the country, season extension involves counteracting the effects of cold weather and frost. For vegetable growers in south Florida, season extension must counteract rising summer temperatures, heavy precipitation, and the resulting increased humidity. One possibility for season extension in the Southern U.S. and south Florida in particular involves the use of high tunnels, offering several potential benefits to south Florida growers. First, high tunnels counteract heavy summer rains by allowing growers to control the amount of water reaching their plants. In doing so, growers minimize the risk of flooding out crops during heavy summer downpours that can result in plant loss.

Second, the ability to limit the water that reaches the plants by decrease both disease and pest pressure. Limiting the variability in the amount of water reaching plants allows for appropriate, consistent irrigation under a grower’s control. This consistent irrigation then contributes to optimal plant development, which in turn increases plants’ resiliency in the face of diseases and pests.

Third, compared to other structural options for season extension (e.g., full greenhouse set-ups with temperature and humidity control), high tunnels have lower start-up costs, offering affordability for growers who are looking for ways to extend their season. This is particularly true for growers working in smaller farming operations who may not be able, within a reasonable time frame, to earn back the capital required to establish more extensive set-ups. Thus, high tunnels offer an economically sustainable option for growers from smaller operations. Similarly, high tunnels are more easily installed over a larger area compared to a greenhouse, further increasing their economic viability for many different operation sizes.