Pecan growers cultivate pecan trees on a commercial basis, harvest and dry the pecan nuts, and supply them to markets around the world. Commercial pecan cultivation requires an in-depth knowledge of irrigation, fertilization, pest prevention, tree pruning, pollination, harvesting and marketing.
To stay abreast with new developments in pecan cultivation and new markets for pecan nuts, many pecan tree growers participate in professional associations like those of the southeastern pecan growers, the western pecan growers and the northern pecan growers. These associations are specific to the U.S., which produces around 80% of the world's pecan nuts; other pecan-producing countries are Argentina, Australia, China, Israel, Mexico and South Africa. American associations cooperate with other international associations like the Australian pecan growers association, and organize conventions and maintain informative websites to promote an exchange of knowledge and expertise amongst pecan cultivators.
There are numerous pecan nut varieties, but it has become common for pecan growers to plant grafted trees that can produce the large, meaty pecan nuts that are in demand commercially. Since pecan trees are long-lived, grow to massive heights and have extensive root systems, the trees are usually planted at least 10.9 yards (10 m) to 21.9 yards (20 m) apart to facilitate healthy growth; keeping a similar distance between two adjoining pecan tree rows is also recommended. Sometimes, in case of unavailability of sufficient land, a pecan grower may plant trees closer together and, after several years of harvesting a bountiful nut crop, may chop down some of the trees as they began to crowd one another. Pecan tree wood has good value, so from the commercial point of view, this can be a profitable investment for a pecan grower.
While pecan trees are generally quite hardy, it is important to guard the trees against weeds and pests. The trees are regularly pruned to get rid of dead wood, to facilitate easy movement around the trees, and to keep the trees at a manageable height. If the trees grow too tall, it can be difficult or impossible to both spray them with pesticides and to harvest the nuts when they are ripe. For good pecan nut production, it is also necessary to ensure that the trees receive plentiful water supply and nutrients. Pecan nuts generally develop from September to November, and are ready to be harvested by May.
To harvest the nuts, pecan growers may either shake the tree manually or by machine. They may lay out nets or mats to catch the falling nuts. The fallen nuts may be gathered manually or by machine. It is important not to let the nuts lie on the ground too long as, with their thin kernels, they are liable to absorb undesirable flavors from the soil. The nuts, once collected, are dried and graded. They are then ready to be shipped to market.