Squash, Gourd, and Pumpkin

Squashes are warm season annuals, preferring 75 to 86 degrees F daytime and 64 degrees F night temperatures. They germinate most rapidly at 86 degrees F soil temperatures. Irrigation is not usually necessary for winter squash, but summer squash respond well. Summer squash is normally planted as soon as temperatures are sufficiently warm, about April 20 in eastern North Carolina. Fall squash crops can also be planted midsummer in areas where virus transmission is not a problem. Planting of pumpkins is delayed until midsummer to avoid having to store the crop until Halloween.

Flowering

Squash plants produce male flowers 3 to 4 days before producing female flowers. Usually three male flowers are formed for each female, but temperature and photoperiod can change this ratio. Female flowers are open for only one day and only from dawn until 10 a.m. Pollination is most successful before 9 a.m. It is important to ensure adequate pollen is deposited on female flowers. One strong hive of honeybees per acre is recommended for squash pollination. The number and weight of seeds and overall fruit shape and size is determined by the amount of pollen deposited on the stigma. In summer squash, if pollination and fertilization are incomplete, the small fruits turn yellow, shrivel and fall off within a few days or are small and misshapen. Squash pollen is large, and not easily moved by insects. The native squash bee does the best job of pollination but is usually not available commercially. Honeybees are too small to easily carry the heavy pollen sacs and generally are most active in late morning when many squash flowers have already closed. In addition, they may leave the fields for nearby crops or wild species.