Imperial County Overview
Imperial County is located in the southwestern corner of southern California. The Laguna Mountains block out incoming coastal moisture. Without water, the areas is a dry, barren desert. Located on the eastern edge of the county, the Colorado Rivers supplies irrigation water for a half million acres of farmland. Saline drainage water flows north to the Salton Sea, a body of water more saline than the ocean. Mexico is the southern border of the county.
Soils consist of very fertile, alluvial deposits from the Colorado River flood plain. These soils may be as deep as a mile in places. Nitrogen and phosphorus fertilizers are needed for vegetable production.
Winters are mild and dry with daily maximum temperatures in the 65 to 75ºF (18-24ºC). Summers are extremely hot with daily maximum temperatures of 104 to 115ºF (40-46ºC). The annual rainfall is just over 3 inches (7.5 cm) with most of it coming in late summer or midwinter.
Imperial Valley has a well-known reputation for midwinter salad vegetables. Shipments of crisphead lettuce, leaf lettuce, cauliflower, broccoli, and cabbage start in December and continue until March. Asparagus is in-season January, February and March. Carrots are harvested January to June.
Spring production of warm-season vegetables starts in late April with the harvest of Sweet Imperial onions, sweet corn, bell pepper, chili peppers, cantaloupes, mixed melons and watermelons.
As of 2015, the total annual vegetable production of Imperial cCounty is around 121,000 acres (48,950 ha) worth roughly $800 million.