Windbreaks reduce wind speed and modify the microclimate in sheltered areas. Many producers use wind barriers in their production systems, but few producers recognize all of the benefits available or understand the principles involved in windbreak function and design. Wind has direct and indirect effects on plant growth and development. Direct effects include soil abrasion, increased transpiration, and lodging. Indirect effects are based on changes in the crop microclimate, which influence plant growth and yield. Windbreaks increase soil and air temperatures and can extend the growing season in sheltered areas, resulting in increased crop development, earlier crop maturity, and market advantage. Plant-water relations and irrigation efficiency are improved by shelter. Overall, modifications to the microclimate in sheltered areas contribute to 5% to 50% higher crop yields. Winds in excess of about 5 m·s −1 (1.0 m·s −1 = 2.25 miles/h; miles/h × 0.447 = m·s −1 ) result in wind erosion and soil abrasion and may cause a loss of crop stand. Wind speeds below 5 m·s −1 may have an equally adverse impact on crop quality and marketable yield. In both cases, wind-breaks can reduce damage effectively in sheltered areas. Wind protection reduces certain problems associated with plasticulture under windy conditions.