Most gardeners start their orange trees indoors and wait until they are older to move them outside, as young orange plants are especially susceptible to cold and to foraging by small animals. However, if you live in the deep south you have the option of planting your orange seeds directly into the ground and avoiding the hassle of transplanting later on. However, if you're looking forward to juicy oranges fresh from your backyard, be aware that the grocery store orange seed that you have planted may be from a hybrid tree and therefore unable to produce fruit. Also, you won't know what sort of tree you're dealing with until anywhere from 7 to 15 years down the line when your orange tree is finally mature enough to bear fruit -- if it can.
Peel the orange and remove the seeds. Thoroughly rinse them to remove any flesh that may cling to them.
Throw away any seeds that are noticeably undersized.
Drop the seeds in a glass of water. Throw away any seeds that float to the top. Keep in mind that smaller seeds may float because of air bubbles clinging to their hulls. Remove the seeds from the glass.
Choose a seed (or many seeds, depending on how many orange trees you want to plant) and wrap it in a moistened paper towel. Then place that paper towel in a plastic bag and store it in your refrigerator's vegetable crisper for one month.
Choose a planting site for your orange seed. Orange trees thrive on sunlight, so pick a spot that provides as much direct sunlight as possible, although orange trees can also tolerate partial shade if necessary. Avoid any spots that drain poorly or remain wet after a substantial rain.
Remove any grass or weeds (and their root systems), rocks or other debris in a five-foot circle that is centered on your ideal planting location.
Dig a hole in the center of the circle three feet wide and two feet deep. Amend the excavated soil with well-aged organic compost. Then refill the hole and tamp the soil with your feet to remove any air pockets. Allow the amended soil to mature for one month while the seed chills in the refrigerator.
Retrieve the orange seed from the refrigerator and soak it in water for three hours.
Plant the seed in the soil, one-half inch deep, and mark the spot where you planted it. This is best done in late spring or early summer.
Water the ground thoroughly.