Orange trees are very attractive, with shiny green leaves, fragrant white flowers and, of course, oranges. Grown outdoors, orange trees prefer warmer, more humid climates, growing best in subtropical conditions, usually in zones 9 or 10. However, oranges can be grown indoors as ornamentals and can even flower and bear fruit, given the right amount of light and moisture. Other than seedless varieties, such as the naval orange, most oranges have several seeds you can germinate at home to raise your own orange tree.
Cut open an orange and remove the seeds.
Prepare a planting medium by mixing equal amounts of potting soil and sand. Cut the drinking cups down to about 3 inches tall and punch holes in the bottom for drainage. Fill the cups with the planting medium.
Plant the seeds, while they are still fresh and moist. Insert one seed approximately ½ inch deep in each cup. Cover the seeds with potting medium and water lightly.
Place each cup in a zip-top plastic bag and seal the bag. Put the cups in a warm place to encourage them to germinate. Keep the soil damp but not wet.
Check the seeds after about a week or two for signs of growth. Once the seeds have sprouted, remove the plastic wrap. After the seedlings have three to four leaves on them, transplant each seedling to a 1-gallon pot.