Market gardeners can grow crops year-round with season extension techniques. Cultural practices, plastic mulches, row covers, and low tunnels provide growers with earlier, later, and higher-quality produce that can capture more markets and demand higher prices. High tunnels or hoophouses, which are essentially unheated greenhouses, have gained increased interest around the country in the past 10 years. Many growers now consider hoophouses essential to the success of their market gardens; they are the focus of research projects, workshops, and new manuals. This publication describes these season extension techniques and provides sources for equipment, supplies, and further information.