As one of the most popular crops in the United States, 1.5 billion pounds (680,000,000 kilograms) of pumpkins are produced each year. The top pumpkin-producing states include Illinois, Indiana, Ohio, Pennsylvania, and California.
According to the Illinois Department of Agriculture, 95% of the U.S. crop intended for processing is grown in Illinois. Nestlé, operating under the brand name Libby's, produces 85% of the processed pumpkin in the United States. In the fall of 2009, rain in Illinois devastated the Nestlé crop, resulting in a shortage affecting the entire country during the Thanksgiving holiday season.
Pumpkins are a warm-weather crop that is usually planted in early July. The specific conditions necessary for growing pumpkins require that soil temperatures three inches (7.6 cm) deep are at least 60 °F (15.5 °C) and soil that holds water well. Pumpkin crops may suffer if there is a lack of water or because of cold temperatures (in this case, below 65 °F (18.3 °C); frost can be detrimental), and sandy soil with poor water retention or poorly drained soils that become waterlogged after heavy rain. Pumpkins are, however, rather hardy, and even if many leaves and portions of the vine are removed or damaged, the plant can very quickly re-grow secondary vines to replace what was removed.
Pumpkins produce both a male and female flower; honeybees play a significant role in fertilization. Pumpkins have historically been pollinated by the native squash bee Peponapis pruinosa, but this bee has declined, probably due to pesticide sensitivity, and today most commercial plantings are pollinated by honeybees. One hive per acre (4,000 m² per hive) is recommended by the U.S. Department of Agriculture. If there are inadequate bees for pollination, gardeners often have to hand pollinate. Inadequately pollinated pumpkins usually start growing but abort before full development. An opportunistic fungus is also sometimes blamed for abortions.