When planted in the right conditions, orange (Citrus sinensis) will produce fruit multiple times a year for many years. A key crop in Florida and Southern California, oranges also grow well in the Rio Grande Valley region of Texas. Orange trees require moderate to high heat to produce sugars and are sensitive to cold. Orange trees thrive in U.S. Department of Agriculture Plant Hardiness Zones 8b-11.
When selecting a spot for an orange tree, it is important to consider not only the type of soil, but how well it drains, pH level and available nutrients. Trees should be planted where soil is deep.
Throughout Florida, orange trees perform best in loose, sandy soil, known as Lakeland fine sand, high hammock soil or high pineland soil. These soils do not hold water and keep the trees from becoming soaked; however, they may lack the proper nutrients and should be amended with fertilizer.
Deep, loamy soil has been shown to be the best soil for orange trees in California. Like its sandy counterpart, loamy soil does not hold water and drains quickly, keeping the roots from getting overwatered. If you are in an area with loamy soil that does not drain well, it may be amended by adding organic matter, such as sawdust or garden compost, to improve drainage.
If you are in an area that does not have good soil for orange trees, you may plant trees in a raised bed or, before planting, dig down to 1 foot and amend existing soil with a layer of organic matter, such as sawdust or garden compost.
Soil pH is the acidity or alkalinity of soil and soil with a pH of 7.0 is considered neutral. Acidic soil has a pH reading of less than 7.0, while alkaline soil has a pH reading of more than 7.0. Orange trees thrive in soil that is neutral, slightly acidic or slightly alkaline, and trees will begin to suffer if acidity or alkalinity increases dramatically.
You may test the pH of your soil with a simple kit, that is available at most commercial garden centers. The pH of soil may be increased by adding lime, or decreased by adding sulfur or aluminum sulfate.
Nitrogen is key to the development of orange trees, and has an affect on a tree's yield. If you are planting in sandy soil, it is particularly important to add nitrogen, and you may do so by using a complete fertilizer. Citrus-specific fertilizers are available at garden shops in areas where trees are grown. In addition, nitrogen may be added separate from the fertilizer, at a rate of 1 lb. to 1 1/2 lbs. annually after the tree is established.