is placing the seeds between two sheets of damp paper towel until they germinate and then planting them, although many cultivators just set the seeds straight into the soil. Commercially grown orange trees are propagated asexually by grafting a mature cultivar onto a suitable seedling rootstock to ensure the same yield, identical fruit characteristics, and resistance to diseases throughout the years. Propagation involves two stages: first, a rootstock is grown from seed. Then, when it is approximately one year old, the leafy top is cut off and a bud taken from a specific scion variety, is grafted into its bark. The scion is what determines the variety of orange, while the rootstock makes the tree resistant to pests and diseases and adaptable to specific soil and climatic conditions. Thus, rootstocks influence the rate of growth and have an effect on fruit yield and quality. Rootstocks must be compatible with the variety inserted into them because otherwise, the tree may decline, be less productive, or die. Among the several advantages to grafting are that trees mature uniformly and begin to bear fruit earlier than those reproduced by seeds (3 to 4 years in contrast with 6 to 7 years), and that it makes it possible to combine the best attributes of a scion with those of a rootstock. Harvest Canopy-shaking mechanical harvesters are being used increasingly in Florida to harvest oranges. Current canopy shaker machines use a series of six-to-seven-foot-long tines to shake the tree canopy at a relatively constant stroke and frequency. Normally, oranges are picked once they are pale orange. Degreening Oranges must be mature when harvested. In the United States, laws forbid harvesting immature fruit for human consumption in Texas, Arizona, California and Florida. Ripe oranges, however, often have some green or yellow-green color in the skin. Ethylene gas is used to turn green skin to orange. This process is known as "degreening", also called "gassing", "sweating", or "curing". Oranges are non-climacteric fruits and cannot post-harvest ripen internally in response to ethylene gas, though they will de-green externally. Storage Commercially, oranges can be stored by refrigeration in controlled-atmosphere chambers for up to twelve weeks after harvest. Storage life ultimately depends on cultivar, maturity, pre-harvest conditions, and handling. In stores and markets, however, oranges should be displayed on non-refrigerated shelves. At home, oranges have a shelf life of about one month. In either case, optimally, they are stored loosely