High tunnels are plastic-covered, passively ventilated and heated structures where crops are grown directly in soil. They have become important tools for Iowa specialty crop producers to increase production of quality crops, extend the season, and increase profitability. The environment in a high tunnel, without rainfall, limited space, and potential climate control requires a unique set of crop management skills. High tunnel production is primarily dominated by tomatoes. Interest among growers focuses on year-round production in high tunnels.
High tunnel production is increasing in Iowa as they provide protection from wind and frost and help extend the growing season. Although production aspects inside high tunnels are similar to field production, high tunnel environment is challenging especially when it comes to temperature management. During summer, temperatures rise fairly quickly in high tunnels and can detrimentally affect crop growth and development. It is not uncommon to see temperatures above 100 degrees F inside high tunnels.