Orange trees grown from seed often tend to produce sour oranges. The two most common ways of propagating sweet orange trees is via grafting and cuttings. Although grafting is more common, you can grow orange trees from branch cuttings. By taking cuttings when the plant is engaged in its most vigorous growth, such as late spring or early summer, you can increase your chances of success with growing a tree from a cutting.
Take a cutting from a current year's branch. Don't take the cutting so soon that the branch is soft and pliable--wait until it has a little woody substance. Make the cut with a sharp knife at about a 45-degree angle to the branch.
Make three or four vertical cuts from the 45-degree angle, 1 inch up the cutting. These wounds will encourage root production.
Pour a small amount of rooting hormone into a bowl and roll the end of the cutting in the hormone.
Fill your pot with potting soil and make a 1-inch-deep hole with your finger. Making this hole will help prevent the rooting hormone from being removed by the soil, as it would be if you simply pressed the cutting down into the soil.
Use your fingers to gently press the soil in around the cutting.
Water the pot to the point that the soil is moist, but not soaking wet.
Wrap the pot and cutting with plastic wrap to prevent the soil from drying out. Think of the plastic wrap as a "miniature greenhouse."
Make sure you add enough water to keep the soil from drying out. Remove the plastic wrap over several days by making small cuts in the wrap to slowly acclimatize the cutting to natural humidity conditions. After about a week of making 1-inch-long cuts, you can remove the wrap.