When the catkins mature, huge quantities of pollen are shed, which increase the chances that the windblown pollen will land on the stigmas of the female flowers. Should the catkins mature before or after the female flower is receptive, pollination does not occur. The fruits develop only after the female flowers are pollinated and the ovules are fertilized by male cells from the pollen. Usually, within a pecan cultivar, pollen shedding does not closely overlap the period when the stigma is receptive. This condition is called dichogamy, which tends to ensure cross-fertilization.
Pecan cultivars differ in the order that the staminate and pistillate flowers mature.
Despite dichogamy, some self-pollination can be expected. The primary reason is that many home gardeners will not be able to spray to control destructive diseases. The varieties recommended for landscape tree plantings are listed in Table 1. To ensure good pollination, plant at least two of these varieties. This is especially important for areas with few surrounding pecan trees.