The state of Florida is famous for its oranges. Multiple varieties exist--Florida growers take advantage of many in their mostly frost-free climate. Some popular varieties include the Navel orange, which has no seeds; Hamlin; Ambersweet; Valencia, which is best for juicing; and several varieties of tangerines and tangelos. If you live in an area that has mild winters (USDA climate zones 8 and higher), you can grow any of these oranges and pretend you're in Florida. If your winters get a little colder, you can grow your orange tree in a large pot and move it indoors during winter. Whichever variety you choose, the directions are the same for all.
Test your soil with an inexpensive soil test kit: oranges prefer a slightly acidic soil, with a pH above 7.0. If your soil tests significantly higher than 7.0, add sulfur. If it tests lower, add hydrated lime and then test your soil again.
Prepare a planting area for your orange tree where it will receive full sun. Well-drained soil is a must for all orange trees, so dig in a generous amount of compost into your planting hole, which you should dig slightly larger than your plant's root ball.
Remove your tree from its nursery pot and gently loosen the roots. Place your tree into the hole you dug and then backfill with the soil/compost you dug out. Tamp the soil down in your planting area and water your tree well. Make certain not to plant your orange in a depression because standing water can cause the roots to rot.
Plant your orange in a large container with a drainage hole if you prefer. Fill the pot with standard potting mix to a level that will allow the tree to sit with its crown, or bottom portion of its trunk, level with the soil after you fill it in. Water, fertilize and care for your potted orange tree the same as for oranges in the ground, but move it under cover in fall.
Fertilize your orange tree four or five times between early spring and early fall. If you purchase a fertilizer designed for citrus, you can eliminate the guesswork of calculating how many pounds of nitrogen and other nutrients to feed it. Follow label instructions. Oranges also respond well to a mulch of rich organic matter, such as compost.
Keep your orange tree pruned to a size and shape that fits with your available space and your landscape. Always cut off dead branches and all branches that emerge from the trunk 1 foot or lower from ground level. Remove water sprouts, or suckers, that you see growing out of the lower trunk or root system. Prune all branches all the way back to the main trunk, without cutting into the trunk.
Protect your tree from frost by draping a blanket or black plastic over it on evenings when the weather is forecast to drop below 32 degrees Fahrenheit.
Apply a fungicide such as sulfur if your tree begins to show signs of powdery mildew, a sooty white or gray substance on its leaves. Pruning will help to improve air circulation among the branches, which will help to prevent fungal diseases.